Re-add a nightly workflow.

Author: kellertuer

.github/workflows/nightly.yml

@@ -0,0 +1,23 @@
+name: nightly
+on:
+  pull_request:
+
+jobs:
+  test:
+    name: Julia ${{ matrix.julia-version }} - ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        julia-version: ["pre"]
+        os: [ubuntu-latest, macOS-latest, windows-latest]
+    steps:
+      - uses: actions/checkout@v4
+      - uses: julia-actions/setup-julia@v2
+        with:
+          version: ${{ matrix.julia-version }}
+          arch: x64
+      - uses: julia-actions/cache@v2
+      - uses: julia-actions/julia-buildpkg@v1
+      - uses: julia-actions/julia-runtest@v1
+        env:
+          fail_ci_if_error: false