singularity: use "run" command more consistently

Author: mr-c

cwltool/singularity.py

@@ -510,7 +510,7 @@ def create_runtime(
         runtime = [
             "singularity",
             "--quiet",
-            "run" if is_apptainer_1_1_or_newer() or is_version_3_10_or_newer() else "exec",
+            "run" if (is_apptainer_1_1_or_newer() or is_version_3_10_or_newer()) else "exec",
             "--contain",
             "--ipc",
             "--cleanenv",