Support for PHP 8

[kevinpapst]

Description

LOOKING FOR HELP WITH TESTING!

TODO BC breaks

• document necessary plugin updates
• document requirement bump to PHP 7.3

FIXED

• Blocked by DDL migrations produce errors on PHP 8.0 + MySQL in transactional mode doctrine/migrations#1104
• Check PHP 8.0 support PHP-CS-Fixer/PHP-CS-Fixer#4702 and the PHP_CS_FIXER_IGNORE_ENV=1 syntax
• Blocked by Doctrine (see Bump PHP requirement to 7.3 as of DBAL 2.11.0 doctrine/dbal#4078 and [2.12] PHP 8 compatibility doctrine/dbal#4347)
• Blocked by use stable PHP 8 releases in the CI FriendsOfSymfony/FOSRestBundle#2278 (actually willdurand/negotiation)
• Blocked by Support PHP 8 handcraftedinthealps/RestRoutingBundle#8

Checklist

• I verified that my code applies to the guidelines (composer code-check)
• I updated the documentation (see here)
• I agree that this code is used in Kimai and will be published under the MIT license

[codecov]

Codecov Report

Merging #2158 (b221b48) into master (df6bd30) will decrease coverage by 0.11%.
The diff coverage is 84.21%.

❗ Current head b221b48 differs from pull request most recent head f510c36. Consider uploading reports for the commit f510c36 to get more accurate results

@@             Coverage Diff              @@
##             master    #2158      +/-   ##
============================================
- Coverage     92.79%   92.67%   -0.12%     
- Complexity     6738     6740       +2     
============================================
  Files           616      616              
  Lines         20135    20142       +7     
============================================
- Hits          18684    18667      -17     
- Misses         1451     1475      +24     

Impacted Files	Coverage Δ
src/Controller/DoctorController.php	73.55% <78.57%> (-1.01%)	⬇️
...Transformer/DurationStringToSecondsTransformer.php	88.88% <100.00%> (ø)
src/Ldap/LdapUserProvider.php	94.28% <100.00%> (ø)
src/Repository/RolePermissionRepository.php	100.00% <100.00%> (ø)
src/Security/DoctrineUserProvider.php	94.44% <100.00%> (ø)
src/Utils/LocaleHelper.php	100.00% <100.00%> (ø)
...rc/Controller/Reporting/ReportByUserController.php	80.18% <0.00%> (-14.42%)	⬇️
src/Ldap/LdapDriver.php	65.30% <0.00%> (-10.21%)	⬇️