ci: manage pre-commit hook updates with Dependabot (#1609)

## Summary
- add a monthly Dependabot job for `.pre-commit-config.yaml` hook
updates
- request `@nv-legate/devops-reviewers` on both GitHub Actions and
pre-commit Dependabot PRs
- remove the stale `pre-commit.ci` autoupdate stanza from
`.pre-commit-config.yaml`
- align pre-commit dependency automation with `legate.internal`

Refs nv-legate/legate.internal#3640

Author: marcinz

.github/dependabot.yml

@@ -10,9 +10,25 @@ updates:
     schedule:
       # Check for updates to GitHub Actions every week
       interval: "weekly"
+    reviewers:
+      - "nv-legate/devops-reviewers"
     labels:
       - CI
     groups:
       gha-all:
         patterns:
           - "*"
+
+  - package-ecosystem: "pre-commit"
+    directory: "/"
+    schedule:
+      # Check for updates to pre-commit hooks every month
+      interval: "monthly"
+    reviewers:
+      - "nv-legate/devops-reviewers"
+    labels:
+      - CI
+    groups:
+      pre-commit-all:
+        patterns:
+          - "*"

.pre-commit-config.yaml

@@ -56,8 +56,5 @@ repos:
         stages: [pre-commit]
         exclude: '^src/cupynumeric/cupynumeric_c\.h$'
 
-ci:
-  autoupdate_schedule: quarterly
-
 default_language_version:
   python: python3