Makefile: rm gen files before generating

This ensures that we can detect changes when a file is no
longer being generated.

Author: johanbrandhorst

Makefile

@@ -2,5 +2,6 @@ BUF_VERSION:=1.35.1
 SQLC_VERSION:=1.26.0
 
 generate:
+	rm -rf $$(pwd)/proto/*.pb.go $$(pwd)/users/db.go $$(pwd)/users/models.go $$(pwd)/users/querier.go $$(pwd)/users/users.sql.go
 	docker run -v $$(pwd):/srv -w /srv bufbuild/buf:$(BUF_VERSION) generate
 	docker run -v $$(pwd)/users:/srv -w /srv sqlc/sqlc:$(SQLC_VERSION) generate