commit code-generated msgpack parser on releases (#8640)

Noticed that the structs code-generated parsers is no longer committed
when we cut a release, starting with v0.12.  We've been committing
generated code to ease reproduction and rebuilding the tag.

Note for example that `structs.generated.go` was present in the [0.11.3
commit](8918fc804a)
but not in the [0.12.1
one](14a6893a25).

We leave the files ignored, so developers don't accidentally commit them
in local development.

scripts/release/Makefile.linux

@@ -22,6 +22,7 @@ build_releases:
 
 	@echo "======>> committing generated files"
 	git add -A .
+	find . -name '*.generated.go' -not -path './vendor/*' -exec git add -f '{}' \;
 # skip comitting files if there are no generated files
 # if prerelease process was a no-op
 	if ! git diff-index --quiet HEAD --; \