Remove single-commit option in build workflow

Remove single-commit option from deployment step.

Author: henilp105

.github/workflows/build.yml

@@ -66,6 +66,5 @@ jobs:
           branch: gh-pages
           folder: build/html
           clean: false
-          single-commit: true
           git-config-email: 53436240+fortran-lang@users.noreply.github.com
           git-config-name: Fortran