ci: add trigger workflow for updating git submodules

.github/CODEOWNERS

@@ -0,0 +1 @@
+* @phylum-dev/engineering

.github/workflows/update_submodule.yml

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+# This is a workflow for updating the external repositories contained in this repository as git submodules.
+#
+# It is configured to be triggered by repository dispatch events which come from outside of this repository.
+# It requires write access to the repository by providing a personal access token (PAT) with `repo` scope.
+#
+# The `event_type` parameter is expected to be `trigger-update-submodule`.
+# The `client_payload` parameter is expected to contain the following data:
+#   * `repo_name`: a string containing the `phylum-dev` repository name to update
+#   * `tag_name`: a string containing the release tag to use for updating the git submodule
+#
+# Here is an example repository dispatch event, triggered with `curl` from the command line:
+#
+# curl \
+#   -X POST \
+#   --fail-with-body \
+#   -H "Accept: application/vnd.github+json" \
+#   -H "X-GitHub-Api-Version: 2022-11-28" \
+#   -H "Authorization: token <PAT>" \
+#   -d '{"event_type":"trigger-update-submodule","client_payload":{"repo_name":"cli","tag_name":"v6.0.1"}}' \
+#   https://api.github.com/repos/phylum-dev/documentation/dispatches
+#
+# References:
+# https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#repository_dispatch
+# https://docs.github.com/en/rest/repos/repos#create-a-repository-dispatch-event
+---
+name: Update Submodules
+
+on:
+  repository_dispatch:
+    types: [trigger-update-submodule]
+
+jobs:
+  bump:
+    name: Update submodules and create PR
+    runs-on: ubuntu-latest
+    env:
+      REPO_NAME: ${{ github.event.client_payload.repo_name }}
+      TAG_NAME: ${{ github.event.client_payload.tag_name }}
+    steps:
+      - name: Checkout the repo
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+
+      - name: Update submodule
+        run: git -C "ext/${REPO_NAME}" checkout "${TAG_NAME}"
+
+      - name: Commit changes
+        run: |
+          git config user.name 'phylum-bot'
+          git config user.email '[email protected]'
+          git add "ext/${REPO_NAME}"
+          git commit -m "build: update \`${REPO_NAME}\` submodule to \`${TAG_NAME}\`"
+          git push --force origin "HEAD:update-${REPO_NAME}-submodule"
+
+      - name: Create Pull Request
+        uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea # v7.0.1
+        with:
+          github-token: ${{ secrets.GH_RELEASE_PAT }}
+          script: |
+            const repo = process.env.REPO_NAME;
+            const tag = process.env.TAG_NAME;
+            const response = await github.rest.pulls.create({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              head: "update-" + repo + "-submodule",
+              base: context.ref,
+              title: "build: update `" + repo + "` submodule to `" + tag + "`",
+              body: "This submodule update was triggered by a " + repo + " release "
+                  + "and ensures the documentation stays current.",
+            });
+            console.log(response);