InvalidSpecError: Invalid spec: =2.7 when installing usaddress=0.5.10 from conda-forge with Python 3.7

Issue: I am getting this error when trying to install the usaddress within my conda environment:

`InvalidSpecError: Invalid spec: =2.7`

Here are the conda commands that I am using:

```
conda create --clone arcgispro-py3 --name arcgispro-py3-clone
activate arcgispro-py3-clone
conda config --env --append channels conda-forge
conda install usaddress=0.5.10 -c conda-forge
```

The [latest version of usaddress](https://anaconda.org/conda-forge/usaddress/files) is from 3 years ago and supports Python 3.6. I'm hoping that an updated conda package can be released for Python 3.7, but I'm still not quite sure why the InvalidSpecError is returning 2.7... Any insight is appreciated!

Environment (conda list):

```
$ conda list
# packages in environment at C:\Program Files\ArcGIS\Pro\bin\Python\envs\arcgispro-py3-clone:
#
appdirs 1.4.4 py_0
arcgis 1.8.3 py37_1668 esri
arcgispro 2.7 0 esri
arcpy 2.7 py37_arcgispro_26810 [arcgispro] esri
argon2-cffi 20.1.0 py37he774522_1
asn1crypto 1.4.0 py_0
async_generator 1.10 py_0
atomicwrites 1.4.0 py_0
attrs 20.2.0 py_0
backcall 0.2.0 py_0
black 19.10b0 py_0
blas 1.0 mkl
bleach 3.2.1 py_0
blinker 1.4 py37_0
brotlipy 0.7.0 py37he774522_1000
cached-property 1.5.2 py_0
certifi 2020.6.20 py37_0
cffi 1.14.3 py37h7a1dbc1_0
cftime 1.0.0b1 py37_0 esri
chardet 3.0.4 py37_1003
click 7.1.2 py_0
colorama 0.4.3 py_0
cppzmq 4.4.1 2 esri
cryptography 2.8 py37_0 esri
cycler 0.10.0 py37_0
decorator 4.4.2 py_0
defusedxml 0.6.0 py_0
despatch 0.1.0 py37_0 esri
entrypoints 0.3 py37_0
et_xmlfile 1.0.1 py_1001
fastcache 1.1.0 py37he774522_0
flake8 3.8.3 py_0
freetype 2.10.1 vc14_0 [vc14] esri
future 0.18.2 py37_0 esri
gdal 2.3.3 arcgispro_py37_16713 [arcgispro] esri
h5py 2.10.0 py37_arcgispro_9 [arcgispro] esri
html5lib 1.1 py_0
icc_rt 2019.0.5 arcgispro_0 [arcgispro] esri
idna 2.10 py_0
importlib-metadata 1.7.0 py37_0
importlib_metadata 1.7.0 0
iniconfig 1.0.1 py_0
intel-openmp 2020.0 arcgispro_166 [arcgispro] esri
ipykernel 5.3.4 py37h5ca1d4c_0
ipython 7.18.1 py37_0 esri
ipython_genutils 0.2.0 py37_0
ipywidgets 7.5.1 py_1
jdcal 1.4.1 py_0
jedi 0.17.2 py37_0 esri
jinja2 2.11.2 py_0
jpeg 9d 0 esri
json5 0.9.4 py37_0 esri
jsonschema 3.2.0 py37_1
jupyter_client 6.1.7 py_0 esri
jupyter_console 6.2.0 py_2 esri
jupyter_contrib_core 0.3.3 py37_3 esri
jupyter_contrib_nbextensions 0.5.1 py37_10 esri
jupyter_core 4.6.3 py37_2 esri
jupyter_highlight_selected_word 0.2.0 py37_2 esri
jupyter_latex_envs 1.4.4 py37_1 esri
jupyter_nbextensions_configurator 0.4.1 py37_1 esri
jupyterlab 2.2.7 py_0 esri
jupyterlab_pygments 0.1.1 py_1 esri
jupyterlab_server 1.2.0 py_0
keyring 21.4.0 py37_0 esri
kiwisolver 1.2.0 py37h74a9793_0
lerc 2.2 py_0 esri
libpng 1.6.37 h2a8f88b_0
libsodium 1.0.18 1 esri
libtiff 4.1.0 0 esri
libxml2 2.9.10 arcgispro_0 [arcgispro] esri
libxslt 1.1.34 he774522_0
lxml 4.5.2 py37h1350720_0
lz4-c 1.9.2 hf4a77e7_3
markupsafe 1.1.1 py37hfa6e2cd_1
matplotlib 3.3.1 py37_arcgispro_0 [arcgispro] esri
mccabe 0.6.1 py37_1
mistune 0.8.4 py37hfa6e2cd_1001
mkl 2020.0 arcgispro_167 [arcgispro] esri
mkl-service 2.3.0 py37hb782905_0
mkl_fft 1.2.0 py37h45dec08_0
mkl_random 1.2.0 py37_0 esri
mpmath 1.1.0 py37_0
mypy_extensions 0.4.3 py37_0
nbclient 0.5.0 py_0 esri
nbconvert 5.6.1 py37_0 esri
nbformat 5.0.7 py_1 esri
nest-asyncio 1.3.2 py_0 esri
netcdf4 1.5.4 py37_arcgispro_5 [arcgispro] esri
networkx 2.5 py37_0 esri
nlohmann_json 3.7.0 1 esri
nose 1.3.7 py37_1004
notebook 5.7.10 py37_0
ntlm-auth 1.4.0 py_0 esri
numexpr 2.7.1 py37h25d0782_0
numpy 1.19.1 py37h5510c5b_0
numpy-base 1.19.1 py37ha3acd2a_0
oauthlib 3.1.0 py_0
olefile 0.46 py37_0
openpyxl 3.0.5 py_0
openssl 1.1.1g 2 esri
packaging 20.4 py_0
pandas 1.1.1 py37ha925a31_0
pandocfilters 1.4.2 py37_1
parso 0.7.0 py_0
pathspec 0.7.0 py_0
pefile 2019.4.18 py_0
pickleshare 0.7.5 py37_1001
pillow-simd 7.1.2 py37_3 esri
pip 20.2.2 py37_0
pluggy 0.13.1 py37_0
pro_notebook_integration 2.7 py37_1 esri
prometheus_client 0.8.0 py_0 esri
prompt_toolkit 3.0.5 py_0 esri
psutil 5.7.2 py37he774522_0
py 1.9.0 py_0
pybind11 2.3.0 1 esri
pycodestyle 2.6.0 py_0
pycparser 2.20 py_2
pyflakes 2.2.0 py_0
pygments 2.7.0 py_0 esri
pyjwt 1.7.1 py37_0
pyopenssl 19.1.0 py_1
pyparsing 2.4.7 py_0
pypdf2 1.26.0 py_2 esri
pyrsistent 0.17.3 py37he774522_0
pyshp 2.1.2 py_0
pysocks 1.7.1 py37_1
pytest 6.1.1 py37_0 esri
python 3.7.9 2 esri
python-certifi-win32 1.2 py37_0 esri
python-dateutil 2.8.1 py_0
pytz 2020.1 py37_0 esri
pywin32-ctypes 0.2.0 py37_0 esri
pywin32-security 228 py37_3 esri
pywinpty 0.5.7 py37_0 esri
pyyaml 5.3.1 py37he774522_1
pyzmq 19.0.2 py37_1 esri
regex 2020.7.14 py37he774522_0
requests 2.24.0 py_0
requests-kerberos 0.12.0 0 esri
requests-negotiate-sspi 0.5.2 py37_1 esri
requests-oauthlib 1.3.0 py_0
requests-toolbelt 0.9.1 py_0
requests_ntlm 1.1.0 py_0 esri
scipy 1.5.2 py37h9439919_0
send2trash 1.5.0 py37_0
setuptools 49.6.0 py37_0
simplegeneric 0.8.1 py37_2
six 1.15.0 py_0
sqlite 3.33.0 h2a8f88b_0
sympy 1.5.1 py37_0 esri
terminado 0.8.3 py37_0
testpath 0.4.4 py_0
toml 0.10.1 py_0
tornado 6.0.4 py37he774522_1
traitlets 4.3.3 py37_0
typed-ast 1.4.1 py37he774522_0
typing_extensions 3.7.4.3 py_0
ujson 3.1.0 py37ha925a31_0
urllib3 1.25.10 py_0
vc 14.1 h0510ff6_4
vs2015_runtime 14.16.27012 hf0eaf9b_0 esri
wcwidth 0.2.5 py_0
webencodings 0.5.1 py37_1
wheel 0.35.1 py_0
widgetsnbextension 3.5.1 py37_0
win_inet_pton 1.1.0 py37_0
wincertstore 0.2 py37_0
winkerberos 0.7.0 py37_1
winpty 0.4.3 4
wrapt 1.12.1 py37he774522_1
x86cpu 0.4 py37_1 esri
xarray 0.16.0 py_0
xeus 0.24.1 1 esri
xlrd 1.2.0 py_0
xlwt 1.3.0 py37_0
xtl 0.6.5 1 esri
xz 5.2.5 h62dcd97_0
yaml 0.2.5 0 esri
zeromq 4.3.2 2 esri
zipp 3.1.0 py_0
zlib 1.2.11 h62dcd97_4
zstd 1.4.5 h04227a9_0
```

Details about conda and system ( conda info ):

```
$ conda info

Current conda install:

platform : win-64
conda version : 4.3.27
conda is private : False
conda-env version : 4.3.27
conda-build version : 3.18.9
python version : 3.6.8.final.0
requests version : 2.22.0
root environment : C:\Program Files\ArcGIS\Pro\bin\Python (writable)
default environment : C:\Program Files\ArcGIS\Pro\bin\Python\envs\arcgispro-py3-clone
envs directories : C:\Program Files\ArcGIS\Pro\bin\Python\envs
C:\Users\Username\AppData\Local\ESRI\conda\envs
C:\Users\Username\.conda\envs
package cache : C:\Users\Username\AppData\Local\ESRI\conda\pkgs
C:\Program Files\ArcGIS\Pro\bin\Python\pkgs
channel URLs : https://repo.anaconda.com/pkgs/main/win-64
https://repo.anaconda.com/pkgs/main/noarch
https://repo.anaconda.com/pkgs/free/win-64
https://repo.anaconda.com/pkgs/free/noarch
https://repo.anaconda.com/pkgs/r/win-64
https://repo.anaconda.com/pkgs/r/noarch
https://repo.anaconda.com/pkgs/msys2/win-64
https://repo.anaconda.com/pkgs/msys2/noarch
https://conda.anaconda.org/conda-forge/win-64
https://conda.anaconda.org/conda-forge/noarch
https://conda.anaconda.org/esri/win-64
https://conda.anaconda.org/esri/noarch
config file : C:\Program Files\ArcGIS\Pro\bin\Python\.condarc
netrc file : None
offline mode : False
user-agent : conda/4.3.27 requests/2.22.0 CPython/3.6.8 Windows/10 Windows/10.0.18362
administrator : True

```