Replace 'upstream' remote by a concrete repo (#72)

Signed-off-by: Juraci Paixão Kröhling <[email protected]>

Makefile

@@ -74,4 +74,4 @@ add-tag:
 push-tag:
 	@[ "${TAG}" ] || ( echo ">> env var TAG is not set"; exit 1 )
 	@echo "Pushing tag ${TAG}"
-	@git push upstream ${TAG}
+	@git push [email protected]:open-telemetry/opentelemetry-collector-releases.git ${TAG}