Actions does not behave the same way as `nix-shell` command

[kha20240826]

Using your action

- name: Test with java
  uses: workflow/nix-shell-action@v3
  with:
    packages: maven,jdk11_headless
    script: |
      java --version;
      mvn --version;

Got me

openjdk 11.0.23 2024-04-16
OpenJDK Runtime Environment (build 11.0.23+0-adhoc..source)
OpenJDK 64-Bit Server VM (build 11.0.23+0-adhoc..source, mixed mode)

Apache Maven 3.9.8 (36645f6c9b5079805ea5009217e36f2cffd34256)
Maven home: /nix/store/6y2p26qfy6qqzrl0wjvdz0hdc6lyl5jy-maven-3.9.8/maven
Java version: 21.0.3, vendor: N/A, runtime: /nix/store/z0hakcf7s1r4wfmwkk6z44wx9b7qfgp3-openjdk-headless-21.0.3+9/lib/openjdk
Default locale: en_US, platform encoding: UTF-8

My maven java version is set to 21 as my jdk version is 11 as the one passed in the packages parameter.

When I'm running the following in my terminal

$ nix-shell -p maven jdk11_headless
$ java --version
$ mvn --version

I got the following result

openjdk 11.0.23 2024-04-16
OpenJDK Runtime Environment (build 11.0.23+0-adhoc..source)
OpenJDK 64-Bit Server VM (build 11.0.23+0-adhoc..source, mixed mode)

pache Maven 3.9.8 (36645f6c9b5079805ea5009217e36f2cffd34256)
Maven home: /nix/store/sf5lp0zlss0mqbzn68ii9qj3mhbf67zk-maven-3.9.8/maven
Java version: 11.0.23, vendor: Oracle Corporation, runtime: /nix/store/8vb9mnp3k0rg4n7bsqc9zqplmyyjs9fc-openjdk-headless-11.0.23+9/lib/openjdk
Default locale: en, platform encoding: UTF-8

Maven java version running in terminal does match the jdk11_headless passing to the command line, if I take maven alone I got jdk21 in my nix shell.

Maybe I don't really understand how nix is supposed to work (I'm a bit new to it) but from my point of view it would have been logical that using this action should have the same behavior as when I'm launching a shell from my local environment.