ci: use codecov token

[sergiud]

@drigz It looks like we do need to set the upload token (CODECOV_TOKEN) because coverage uploads sometimes fail despite previously successful builds:

[2021-12-06T20:25:06.918Z] ['verbose'] The error stack is: Error: Error uploading to https://codecov.io: Error: There was an error fetching the storage URL during POST: 404 - Not Found - {'detail': ErrorDetail(string='Unable to locate build via Github Actions API. Please upload with the Codecov repository upload token to resolve issue.', code='not_found')}

The token can be added in repository Settings -> Secrets -> Repository secrets. The token can be obtained from codecov.

Codecov settings also mention that "Github Integration is installed. However, this repository is not enabled." Thus, glog needs to be whitelisted by following the link on the page which I don't have access to.

[codecov-commenter]

Codecov Report

Merging #752 (a9a9e1e) into master (f4dd77a) will increase coverage by 1.27%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #752      +/-   ##
==========================================
+ Coverage   71.38%   72.65%   +1.27%     
==========================================
  Files          17       17              
  Lines        3208     3211       +3     
==========================================
+ Hits         2290     2333      +43     
+ Misses        918      878      -40     

Impacted Files	Coverage Δ
src/logging.cc	73.68% <0.00%> (+0.92%)	⬆️
src/symbolize.cc	62.82% <0.00%> (+1.72%)	⬆️
src/glog/logging.h.in	82.27% <0.00%> (+4.64%)	⬆️
src/utilities.cc	67.64% <0.00%> (+13.97%)	⬆️

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[drigz]

I've set the repository secret. However, I also lack access to that page. If the problem persists, let me know and I can try to seek out a suitable admin.

[sergiud]

Thanks!