github-ci: port send-telegram-notify to python3

For now python3 is used as the default python on all OS and it is
needed to enable it in send-telegram-notify action.

Found issue:

  Traceback (most recent call last):
    File "<string>", line 3, in <module>
  AttributeError: module 'urllib' has no attribute 'quote_plus'

In Python 3 quote_plus included into urllib.parse.

Check documentaion [1]:

  Note The urllib module has been split into parts and renamed in Python 3 to urllib.request, urllib.parse, and urllib.error.

Check the same issue [2].

This patch changes use of all needed routines just from 'urllib'.

Closes tarantool/tarantool-qa#112

[1]: https://docs.python.org/2/library/urllib.html
[2]: web2py/web2py#1822

Author: avtikhon

.github/actions/send-telegram-notify/action.yml

@@ -5,8 +5,8 @@ runs:
   steps:
     # install 'requests' Python module
     - run: |
-        python -m pip install --upgrade pip ||:
-        pip install requests ||:
+        python3 -m pip install --upgrade pip ||:
+        pip3 install requests ||:
       shell: bash
     # logout github environment
     - env:
@@ -72,8 +72,9 @@ runs:
         fi
         # Use MarkdownV2 while Markdown is legacy
         # https://core.telegram.org/bots/api#markdownv2-style
-        python -c "import urllib, requests ; \\
-          url = 'https://api.telegram.org/bot%s/sendMessage?chat_id=%s&text=%s&parse_mode=MarkdownV2&disable_web_page_preview=true' \\
-            % ('$TELEGRAM_TOKEN', '$send_to', urllib.quote_plus('$msg')) ; \\
-          _ = requests.post(url, timeout=10)"
+        python3 -c "from urllib import request, parse ; \\
+          url = 'https://api.telegram.org/bot%s/sendMessage' % ('$TELEGRAM_TOKEN') ; \\
+          data = parse.urlencode({'chat_id' : '$send_to', 'parse_mode' : 'MarkdownV2', 'disable_web_page_preview' : 'true', 'text' : '$msg'}).encode('ascii') ; \\
+          response = request.urlopen(url=url, data=data, timeout=10) ; \\
+          print(response.read())"
       shell: bash