Check TOML files in pre-commit.

There was a hook before, but it was restricted just to Pipfile. Now scan
all of them.

.pre-commit-config.yaml

@@ -8,6 +8,7 @@ repos:
       - id: check-symlinks
         exclude: >-
           myclirc|netrc|packet-cli|mycli-history|scwrc|gcloud\.json|\.envrc\.private
+      - id: check-toml
       - id: check-toml
         files: Pipfile
       - id: trailing-whitespace