test: Emacs 29.1 (#755)

Author: jcs090218

.github/workflows/test.yml

@@ -15,6 +15,7 @@ concurrency:
 jobs:
   test:
     runs-on: ${{ matrix.os }}
+    continue-on-error: ${{ matrix.experimental }}
     strategy:
       fail-fast: false
       matrix:
@@ -24,7 +25,18 @@ jobs:
           - 27.1
           - 27.2
           - 28.1
-          - snapshot
+          - 29.1
+        experimental: [false]
+        include:
+          - os: ubuntu-latest
+            emacs-version: snapshot
+            experimental: true
+          - os: macos-latest
+            emacs-version: snapshot
+            experimental: true
+          - os: windows-latest
+            emacs-version: snapshot
+            experimental: true
 
     steps:
       - uses: jcs090218/setup-emacs@master