ci(alt_text): reference main for now as no release yet

Author: amyheather

.github/workflows/lint_alt_text.yml

@@ -19,4 +19,4 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: lintquarto/alt-text-linter@v1
+      - uses: lintquarto/alt-text-linter@main