RWS: log a message on startup

[prandla]

Currently, RWS doesn't print any messages at all when starting up, which sometimes makes me worried as to whether it started up properly or not. I added a log line that prints the listening address(es), which is quite common behavior for server programs.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 54.70%. Comparing base (715872a) to head (07630c0).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
cmsranking/RankingWebServer.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1635      +/-   ##
==========================================
- Coverage   54.70%   54.70%   -0.01%     
==========================================
  Files         335      335              
  Lines       27352    27354       +2     
==========================================
  Hits        14963    14963              
- Misses      12389    12391       +2     

Flag	Coverage Δ
functionaltests	0.00% <0.00%> (ø)
unittests	54.70% <0.00%> (-0.01%)	⬇️

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