[composer php] Dependabot updates too many dependencies even with `versioning-strategy: increase-if-necessary`

Hi,

we would like to update with dependabot only our private libraries, but it seems dependabot calls `composer update` with option `--with-all-dependencies`. Thus, we have a lot of libraries updated instead of just the single one(s) that we would like.

Is there a way to remove this option?

thanks a lot.

Start with the Composer updater and its handling of `versioning-strategy: increase-if-necessary`, then trace the reported `composer update --with-all-dependencies` invocation. Done means updates target the requested private libraries without unnecessarily updating unrelated dependencies.

Written by the indexing model from the issue text.