Update parent POM, switch to Renovate, enable dep automerge (jenkinsci#157)

- Update parent POM to 6.2122.v70b_7b_f659d72
- Switch from Dependabot to Renovate
- (Perhaps) enable GHA workflows for dependency automerge

Co-authored-by: Claude <noreply@anthropic.com>

Author: jglick

.github/dependabot.yml

@@ -0,0 +1,6 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": [
+    "github>jenkins-infra/.github:renovate-config"
+  ]
+}

.github/renovate.json

@@ -0,0 +1,9 @@
+name: Automatically approve and merge safe dependency updates
+on:
+- pull_request_target
+permissions:
+  contents: write
+  pull-requests: write
+jobs:
+  auto-merge-safe-deps:
+    uses: jenkins-infra/github-reusable-workflows/.github/workflows/auto-merge-safe-deps.yml@v1

.github/workflows/auto-merge-safe-deps.yml

@@ -0,0 +1,11 @@
+name: Close BOM update PR if passing
+on:
+  check_run:
+    types:
+    - completed
+permissions:
+  contents: read
+  pull-requests: write
+jobs:
+  close-bom-if-passing:
+    uses: jenkins-infra/github-reusable-workflows/.github/workflows/close-bom-if-passing.yml@v1

.github/workflows/close-bom-if-passing.yml

@@ -4,7 +4,7 @@
   <parent>
     <groupId>org.jenkins-ci.plugins</groupId>
     <artifactId>plugin</artifactId>
-    <version>6.2108.v08c2b_01b_cf4d</version>
+    <version>6.2122.v70b_7b_f659d72</version>
     <relativePath />
   </parent>
   <groupId>io.jenkins.plugins</groupId>