Improve coverage following #1274

[tonial]

I've fixed the coverage issue from #1274.
The two lines from the deprecated validate_logout_request() function were not tested in the unit test, only in larger tests that no longer call this function (as the code now uses the view method instead)

Checklist

• PR only contains one change (considered splitting up PR)
• unit-test added
• documentation updated
• CHANGELOG.md updated (only for user relevant changes)
• author name in AUTHORS

[codecov]

Codecov Report

Merging #1317 (4d499d8) into master (fe7b086) will increase coverage by 0.09%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1317      +/-   ##
==========================================
+ Coverage   97.34%   97.44%   +0.09%     
==========================================
  Files          32       32              
  Lines        2073     2073              
==========================================
+ Hits         2018     2020       +2     
+ Misses         55       53       -2     

see 1 file with indirect coverage changes

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more