WARNING: pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.
WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError("Can't connect to HTTPS URL because the SSL module is not available.")': /simple/tf-nightly-gpu/
WARNING: Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError("Can't connect to HTTPS URL because the SSL module is not available.")': /simple/tf-nightly-gpu/
WARNING: Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError("Can't connect to HTTPS URL because the SSL module is not available.")': /simple/tf-nightly-gpu/
WARNING: Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError("Can't connect to HTTPS URL because the SSL module is not available.")': /simple/tf-nightly-gpu/
WARNING: Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError("Can't connect to HTTPS URL because the SSL module is not available.")': /simple/tf-nightly-gpu/
Could not fetch URL https://pypi.org/simple/tf-nightly-gpu/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host='pypi.org', port=443): Max retries exceeded with url: /simple/tf-nightly-gpu/ (Caused by SSLError("Can't connect to HTTPS URL because the SSL module is not available.")) - skipping

同じエラーにあってる方がいるようで、私はこれで解決しました、というのをいくつか試しました。

python を入れなおす
pip を入れなおす
libsslのなんかのdllをpathの上位のほうに持ってくる

私が解消したのは、「OpenSSL 単体を入れなおす」でした。
本家、https://slproweb.com/products/Win32OpenSSL.html からとってきました。lite版とfullがありますが、うちは、liteで行けました。

python 入れ直しとかよりも簡単と思いますのでお試しあれ...