Attempt to automate updating yosys.

.github/workflows/update-yosys.yml

@@ -0,0 +1,48 @@
+on:
+    push:
+    workflow_dispatch:
+    schedule:
+        - cron: '0 0 1 * *'
+
+name: Update Yosys (and OSS Cad Suite)
+
+# https://github.com/peter-evans/create-pull-request/blob/main/docs/concepts-guidelines.md#workarounds-to-trigger-further-workflow-runs
+jobs:
+    update:
+        name: Update OSS Cad Suite Version
+        strategy:
+          matrix:
+            os: [ubuntu-latest]
+        runs-on: ${{ matrix.os }}
+
+        steps:
+            - uses: actions/checkout@v4
+
+            # Yesterday, because CAD suite versions are made at the end of the
+            # night.
+            - name: Update OSS CAD Suite version file (and save new value)
+              run: |
+                date -d today +%Y-%m-%d > ci/oss-cad-suite-version
+                echo >> $GITHUB_ENV OSS_CAD_SUITE_DATE=$(cat ci/oss-cad-suite-version)
+
+            - name: Create Pull Request
+              id: cpr
+              uses: peter-evans/create-pull-request@v5
+              with:
+                token: ${{ secrets.PAT }}
+                commit-message: Update OSS CAD Suite version to ${{ env.OSS_CAD_SUITE_DATE }}
+                committer: GitHub <[email protected]>
+                author: ${{ github.actor }} <${{ github.actor }}@users.noreply.github.com>
+                signoff: false
+                branch: update-yosys-${{ env.OSS_CAD_SUITE_DATE }}
+                delete-branch: true
+                title: Update OSS CAD Suite version to ${{ env.OSS_CAD_SUITE_DATE }}
+                body: |
+                    Auto-generated by [create-pull-request][1]
+
+                    [1]: https://github.com/peter-evans/create-pull-request
+                labels: |
+                    automated pr
+                assignees: cr1901
+                reviewers: cr1901
+                draft: false