Use default pickle protocol

bugbug/repository.py

@@ -802,9 +802,7 @@ def calculate_experiences(commits, first_pushdate, save=True):
 
     if save:
         with open("data/commit_experiences.pickle", "wb") as f:
-            pickle.dump(
-                (experiences, first_commit_time), f, protocol=pickle.HIGHEST_PROTOCOL
-            )
+            pickle.dump((experiences, first_commit_time), f)
 
 
 def set_commits_to_ignore(repo_dir, commits):

bugbug/test_scheduling.py

@@ -28,7 +28,7 @@ def get_test_scheduling_history():
 def get_past_failures():
     return shelve.Shelf(
         LMDBDict("data/past_failures.lmdb"),
-        protocol=pickle.HIGHEST_PROTOCOL,
+        protocol=pickle.DEFAULT_PROTOCOL,
         writeback=True,
     )
 

scripts/past_bugs_by_function.py

@@ -94,7 +94,7 @@ class PastBugsCollector(object):
                     }
 
         with open("data/past_bugs_by_function.pickle", "wb") as f:
-            pickle.dump(past_bugs_by_function, f, protocol=pickle.HIGHEST_PROTOCOL)
+            pickle.dump(past_bugs_by_function, f)
         zstd_compress("data/past_bugs_by_function.pickle")