Add support for sping framework 7

[EmmaBoulangier-cegeka]

Spring framework 7 is released and there are a few breaking changes. One of which is the removal of HttpHeaders.containsKey which is used in multiple places.
Any intention of supporting this?

[schmidthappens]

Added a PR as a proposal to support Spring 7
#1884

[rholshausen]

4.7.0-beta.3 released with the Spring 7 support

[EmmaBoulangier-cegeka]

Thanks so much. Looks great.