!!! TASK: Upgrade psr/container and psr/http-message dependencies to ^2.0

[mficzel]

• Upgrade psr/container dependency from ^1.0 to ^2.0
• Upgrade psr/http-message dependency from ^1.0 to ^2.0

resolves: #3497

Upgrade instructions

If you extend any of the interfaces in the upgraded packages you will have to add the return type informations to the methods you implement and override. Behavior has not been changed but return types.

Review instructions

Not sure wether this can be added to 9.x or wether this has to wait for 10.0. I mark this as breaky for now.

Checklist

• Code follows the PSR-2 coding style
• Tests have been created, run and adjusted as needed
• The PR is created against the lowest maintained branch
• Reviewer - PR Title is brief but complete and starts with FEATURE|TASK|BUGFIX
• Reviewer - The first section explains the change briefly for change-logs
• Reviewer - Breaking Changes are marked with !!! and have upgrade-instructions

[mhsdesign]

yes that makes sense thanks! It was probably due already for the 9.0 release but forgotten ...

for regular projects this should cause no problems and i dont think there are extensions affected by this which would have a hard time supporting now flow 9.0 and 9.1