Can't install Python 3.6.15 on OSX 10.15.7

まだ誰も着手していません。

When I try installing Python 3.6.15 on OSX 10.15.7 it fails:

```
asdf install python 3.6.15
python-build 3.6.15 /Users/trevorbrown/.asdf/installs/python/3.6.15
python-build: use openssl@1.1 from homebrew
python-build: use readline from homebrew
Downloading Python-3.6.15.tar.xz...
-> https://www.python.org/ftp/python/3.6.15/Python-3.6.15.tar.xz
Installing Python-3.6.15...
python-build: use tcl-tk from homebrew
python-build: use readline from homebrew
python-build: use zlib from xcode sdk
ERROR: The Python ssl extension was not compiled. Missing the OpenSSL lib?

Please consult to the Wiki page to fix the problem.
https://github.com/pyenv/pyenv/wiki/Common-build-problems

BUILD FAILED (OS X 10.15.7 using python-build 2.0.6-14-ge56962b3)

Inspect or clean up the working tree at /var/folders/7m/9bq62tmj60zf14d788w0lk8c0000gp/T/python-build.20210917113737.35119
Results logged to /var/folders/7m/9bq62tmj60zf14d788w0lk8c0000gp/T/python-build.20210917113737.35119.log

Last 10 log lines:
install|*) ensurepip="" ;; \
esac; \
./python.exe -E -m ensurepip \
$ensurepip --root=/ ; \
fi
Looking in links: /var/folders/7m/9bq62tmj60zf14d788w0lk8c0000gp/T/tmpimujpeip
Collecting setuptools
Collecting pip
Installing collected packages: setuptools, pip
Successfully installed pip-18.1 setuptools-40.6.2
```

It's not clear to me from the error message and the logs what failed. Installing Python 3.6.13 however succeeds:

```
asdf install python 3.6.13
python-build 3.6.13 /Users/trevorbrown/.asdf/installs/python/3.6.13
python-build: use openssl@1.1 from homebrew
python-build: use readline from homebrew
Downloading Python-3.6.13.tar.xz...
-> https://www.python.org/ftp/python/3.6.13/Python-3.6.13.tar.xz
Installing Python-3.6.13...
python-build: use tcl-tk from homebrew
python-build: use readline from homebrew
python-build: use zlib from xcode sdk
Installed Python-3.6.13 to /Users/trevorbrown/.asdf/installs/python/3.6.13
```

Output from `asdf info`:

```
OS:
Darwin it-mbp-trevorbrown.home 19.6.0 Darwin Kernel Version 19.6.0: Tue Jun 22 19:49:55 PDT 2021; root:xnu-6153.141.35~1/RELEASE_X86_64 x86_64

SHELL:
zsh 5.7.1 (x86_64-apple-darwin19.0)

ASDF VERSION:
v0.8.1-7e1f2a0

ASDF ENVIRONMENT VARIABLES:
ASDF_DIR=/Users/trevorbrown/.asdf

ASDF INSTALLED PLUGINS:
clojure https://github.com/halcyon/asdf-clojure.git master c6125ab
elasticsearch https://github.com/asdf-community/asdf-elasticsearch.git master b908f32
elixir ssh://git@github.com/asdf-vm/asdf-elixir.git master 63e9cd8
erlang git@github.com:asdf-vm/asdf-erlang.git better-logging b90f3ee
java https://github.com/halcyon/asdf-java.git master b050643
kafka git@github.com:JoshAshby/asdf-kafka.git master 6c8660a
lua git@github.com:Stratus3D/asdf-lua.git master ef66ab8
nodejs ssh://git@github.com/asdf-vm/asdf-nodejs.git master 95a2091
postgres https://github.com/smashedtoatoms/asdf-postgres.git master 2fa062b
python https://github.com/tuvistavie/asdf-python.git master 57a4d72
rebar https://github.com/Stratus3D/asdf-rebar.git master f3aa004
ruby git@github.com:asdf-vm/asdf-ruby.git charlesbjohnson-charlesbjohnson/gemfile-parsing 606cb83
yarn https://github.com/twuni/asdf-yarn.git master 5525eb2
```

まず、報告された macOS 環境で `asdf install python 3.6.15` を再現し、その出力を正常に完了した 3.6.13 のインストールと比較します。python-build のログと OpenSSL の設定を調査します。Python 3.6.15 が ssl 拡張機能のコンパイルに成功した状態でインストールできれば完了です。

索引モデルが issue の本文から書いたものです。