Bump `proc-macro-crate` to the latest version (#4409)
This PR bumps `proc-macro-crate` to the latest version. In order to test a runtime from https://github.com/polkadot-fellows/runtimes/ with the latest version of polkadot-sdk one needs to use `cargo vendor` to extract all runtime dependencies, patch them by hand and then build the runtime. However at the moment 'vendored' builds fail due to https://github.com/bkchr/proc-macro-crate/issues/48. To fix this `proc-macro-crate` should be updated to version `3.0.1` or higher. --------- Co-authored-by: command-bot <>