Installation fails on compilation stage of http_client_filter.cc on Centos 7 (with python3)

Versions:
- CentOS Linux release 7.7.1908 (Core)
- cvpi version 2020.2.3-base-4-g56c15e7 go1.13.6

`python3 setup.py install` fails when compiling http_client_filter.cc.
Here is the part of the output with the compiler error:
```
src/core/ext/filters/http/client/http_client_filter.cc: In function ‘grpc_core::ManagedMemorySlice user_agent_from_args(const grpc_channel_args*, const char*)’:
src/core/ext/filters/http/client/http_client_filter.cc:546:58: error: no matching function for call to ‘StrFormat(const char [19], const char*, const char [6], const char*&)’
GPR_PLATFORM_STRING, transport_name));
^
src/core/ext/filters/http/client/http_client_filter.cc:546:58: note: candidate is:
In file included from src/core/ext/filters/http/client/http_client_filter.cc:27:0:
third_party/abseil-cpp/absl/strings/str_format.h:338:34: note: template std::string absl::lts_2020_09_23::StrFormat(absl::lts_2020_09_23::FormatSpec&, const Args& ...)
ABSL_MUST_USE_RESULT std::string StrFormat(const FormatSpec& format,
^
third_party/abseil-cpp/absl/strings/str_format.h:338:34: note: template argument deduction/substitution failed:
src/core/ext/filters/http/client/http_client_filter.cc:546:58: note: mismatched types ‘absl::lts_2020_09_23::FormatSpec’ and ‘const char [19]’
GPR_PLATFORM_STRING, transport_name));
```

The attached file below includes the whole output of the command:
[cloudvision-compile.txt](https://github.com/aristanetworks/cloudvision-python/files/5702305/cloudvision-compile.txt)

Note that in the end there is a secondary problem that has to do with python 3 (the `ModuleNotFoundError: No module named 'commands'` error), but I guess that is only triggered by the gcc error above.

Inizia da src/core/ext/filters/http/client/http_client_filter.cc alla riga 546 e analizza la chiamata segnalata a Abseil StrFormat, quindi riproduci `python3 setup.py install` su CentOS 7 usando le versioni elencate. L'errore di compilazione dovrebbe essere risolto, mentre l'errore rimanente di Python 3 `ModuleNotFoundError: No module named 'commands'` dovrebbe essere verificato separatamente per confermare se l'installazione viene completata.

Scritto dal modello di indicizzazione a partire dal testo della issue.