maint: Add stale github action (#4926)

* maint: Add stale github action

* add changelog entry

* increase close days, add exempt pr labels

* update contributing with stale PRs section

* Update cron schedule

Co-authored-by: Emídio Neto <9735060+emdneto@users.noreply.github.com>

* update stale message

* clean-up

---------

Co-authored-by: Emídio Neto <9735060+emdneto@users.noreply.github.com>

Author: MikeGoldsmith

.github/workflows/stale.yml

@@ -0,0 +1,35 @@
+name: Mark stale PRs
+
+on:
+  schedule:
+    - cron: "12 3 * * *"
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  stale:
+    permissions:
+      contents: read
+      issues: write
+      pull-requests: write
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/stale@b5d41d4e1d5dceea10e7104786b73624c18a190f # v10.2.0
+        with:
+          repo-token: ${{ secrets.GITHUB_TOKEN }}
+          days-before-pr-stale: 14
+          days-before-pr-close: 14
+          days-before-issue-stale: -1
+          days-before-issue-close: -1
+          stale-pr-message: >
+            This PR has been automatically marked as stale because it has not had
+            any activity for 14 days. It will be closed if no further activity
+            occurs within 14 days of this comment.
+
+            If you're still working on this, please add a comment or push new commits.
+          close-pr-message: >
+            This PR has been closed due to inactivity. Please reopen if you would
+            like to continue working on it.
+          exempt-pr-labels: "hold,WIP,blocked by spec,do not merge"

CHANGELOG.md

@@ -12,6 +12,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+- Add stale PR GitHub Action
+  ([#4926](https://github.com/open-telemetry/opentelemetry-python/pull/4926))
 - `opentelemetry-sdk`: Drop unused Jaeger exporter environment variables (exporter removed in 1.22.0)
   ([#4918](https://github.com/open-telemetry/opentelemetry-python/issues/4918))
 - `opentelemetry-sdk`: Clarify timeout units in environment variable documentation

CONTRIBUTING.md

@@ -291,6 +291,12 @@ Please fork this repo in a personal Github account instead.
 
 One of the maintainers will merge the PR once it is **ready to merge**.
 
+### Stale PRs
+
+PRs with no activity for 14 days will be automatically marked as stale and closed after a further 14 days of inactivity. To prevent a PR from being marked stale, ensure there is regular activity (commits, comments, reviews, etc).
+
+Project managers can also exempt a PR from this by applying one of the following labels: `hold`, `WIP`, `blocked by spec`, `do not merge`.
+
 ## Design Choices
 
 As with other OpenTelemetry clients, opentelemetry-python follows the