Lockfile not invalidated when removing platforms

[ruben-arts]

Checks

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pixi, using pixi --version.

Reproducible example

When removing the platforms in a manifest, the lockfile is not invalidated

pixi init repro && cd repro
pixi add python # creates lockfile and installs environment
pixi project platform remove YOUR_PLATFORM # Doesn't update lockfile
pixi remove python # Doesn't update lockfile
pixi install # Doesn't update lockfile

Issue description

We should invalidate the lockfile on a mismatch between the platforms.

Expected behavior

The lockfile is in sync with the manifest after a command that modifies content that is related to the lockfile.