Reduce the number of compat entries in docs and test

This is a feature request. Let some package be called `Foo`. I think that it would be possible to avoid a compat entry for any package in `docs/Project.toml` and `test/Project.toml` for which a compat entry is specified in `Project.toml`, because both `docs` and `test` both depend on `Foo` anyway. Currently, there is a lot of duplication in these compat entries.

For example, when upgrading to DataFrames 1.0, I received two PRs. One for `Project.toml` and one for `test/Project.toml`. When you forget to change one of these compat entries and the entries are strict/narrow, the tests will fail.