maint: Enable pre-commit.ci autoupdates

.pre-commit-config.yaml

@@ -53,3 +53,7 @@ repos:
         # In case of ambiguity (multiple possible corrections), `typos` will just report it to the user and move on without applying/writing any changes.
         # cf. https://github.com/crate-ci/typos
         args: [--write-changes]
+
+# pre-commit.ci config reference: https://pre-commit.ci/#configuration
+ci:
+  autoupdate_schedule: monthly