exclude run.t files from trailing whitespace check

Author: Roman-Manevich

.pre-commit-config.yaml

@@ -42,7 +42,10 @@ repos:
             )|
 
             # Expected files should be left verbatim.
-            \.expected(-failure)?$
+            \.expected(-failure)?$|
+
+            # Cram tests may include trailing whitespace.
+            (^|/)run\.t$
           )
 - repo: https://github.com/arenadotio/pre-commit-ocamlformat
   rev: 0439858f79b3bcb49e757278eb1312e212d7dd4f