Dockerfile: update Composer from 2.3.8 to 2.4.0
Dockerfile: update Composer from 2.3.8 to 2.4.0

https://github.com/composer/composer/releases/tag/2.4.0

smrealms/smr,hemberger/smr,hemberger/smr,hemberger/smr,hemberger/smr,smrealms/smr,smrealms/smr