Bevy release train - add a workflow to manually create a PR updating Bevy version (#3283)

# Objective

- Ensure future Bevy releases happens smoothly

## Solution

- Add a workflow that will open a PR updating all Bevy crate that can be created manually

example PR opened: https://github.com/mockersf/bevy/pull/62

The day from this PR does not need to be the release day, it will just open the PR to prepare it. Later if we feel confident, it could push automatically to crates.io.


how to trigger the workflow: https://docs.github.com/en/actions/managing-workflow-runs/manually-running-a-workflow

.github/workflows/release.yml

@@ -0,0 +1,48 @@
+name: Release
+
+# how to trigger: https://docs.github.com/en/actions/managing-workflow-runs/manually-running-a-workflow
+on:
+  workflow_dispatch:
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  ci:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Install cargo-release
+        run: cargo install cargo-release
+
+      - name: Setup release
+        run: |
+          git config user.name 'Bevy Auto Releaser'
+          git config user.email 'bevy@users.noreply.github.com'
+          # --workspace: updating all crates in the workspace
+          # --no-publish: do not publish to crates.io
+          # --execute: not a dry run
+          # --no-tag: do not push tag for each new version
+          # --no-push: do not push the update commits
+          # --exclude: ignore those packages
+          cargo release minor \
+            --workspace \
+            --no-publish \
+            --execute \
+            --no-tag \
+            --no-confirm \
+            --no-push \
+            --exclude ci \
+            --exclude errors \
+            --exclude bevy-ios-example
+
+      - name: Create PR
+        uses: peter-evans/create-pull-request@v3
+        with:
+          delete-branch: true
+          base: "main"
+          title: "Preparing Next Release"
+          body: |
+            Preparing next release
+            This PR has been auto-generated