chore: explicitly remove temporary merged metal spec after codegen (#93)

The semantic-release tool explicitly ignores the `.gitignore` file,
which means that the automated release process will commit all files
that are present in the local repo even if they are in the `.gitignore`.
This updates the Metal codegen task to explicitly clean up the temporary
merged spec. If swagger-api/swagger-parser#2105 gets merged and is
included in an openapi-generator release before this SDK loses support
for Metal, we can remove the temporary merged Metal spec.

Author: ctreatma

Makefile.metalv1

@@ -65,6 +65,8 @@ codegen:
 		-o /local/${CODE_DIR} \
 		-i /local/${SPEC_BASE_DIR}/${PACKAGE_NAME}/temp_merged_spec/${SPEC_ROOT_FILE}
         # -i /local/${SPEC_PATCHED_DIR}/${SPEC_ROOT_FILE} # switch back to this when the temporary merged spec is removed
+
+	rm -rf /local/${SPEC_BASE_DIR}/${PACKAGE_NAME}/temp_merged_spec
 
 validate:
 	${OPENAPI_GENERATOR} validate \