Update Go version to 1.25.8 in workflow

Author: httpdss

.github/workflows/generate-terminal-gifs.yaml

@@ -24,7 +24,7 @@ jobs:
       - name: Setup Go
         uses: actions/setup-go@44694675825211faa026b3c33043df3e48a5fa00
         with:
-          go-version: '1.25.1'
+          go-version: '1.25.8'
 
       - name: Install VHS dependencies
         run: |