fix: Reenable staleness bot (#535)

* fix: Reenable staleness bot

Reenable staleness bot on the repo

* Update auto-label.yaml

Author: losalex

.github/auto-label.yaml

@@ -13,3 +13,7 @@
 # limitations under the License.
 requestsize:
   enabled: true
+staleness:
+  pullrequest: true
+  old: 30
+  extraold: 60

owlbot.py

@@ -66,6 +66,7 @@
         ".coveragerc", 
         "docs/multiprocessing.rst",
         ".github/workflows", # exclude gh actions as credentials are needed for tests
+        ".github/auto-label.yaml",
         ])
 
 # adjust .trampolinerc for environment tests