[tools/update-ui-test-files.sh] Better support MSRV (#2576)

Author: joshlf

tools/update-ui-test-files.sh

@@ -14,6 +14,10 @@ set -e
 
 TRYBUILD=overwrite ./cargo.sh +nightly test ui --test trybuild -p zerocopy --all-features
 TRYBUILD=overwrite ./cargo.sh +stable  test ui --test trybuild -p zerocopy --features=__internal_use_only_features_that_work_on_stable
-TRYBUILD=overwrite ./cargo.sh +msrv    test ui --test trybuild -p zerocopy --features=__internal_use_only_features_that_work_on_stable
+# For developers using Rust Analyzer, it's often the case that Rust Analyzer has
+# chosen versions of dependencies (especially syn) which have an MSRV higher than
+# our own. Doing `rm Cargo.lock` here permits `./cargo.sh +msrv` to choose its own
+# versions of these crates that have a lower MSRV.
+rm Cargo.lock && TRYBUILD=overwrite ./cargo.sh +msrv    test ui --test trybuild -p zerocopy --features=__internal_use_only_features_that_work_on_stable
 
 TRYBUILD=overwrite ./cargo.sh +all test ui --test trybuild -p zerocopy-derive