lint: Check that python-pre-commit is not an input.

pre-commit should never be a native-input of python packages, it's a
package manager for commit linting that is irrelevant to builds.

* guix/lint.scm (check-inputs-should-not-be-an-input-at-all): Add entry
for python-pre-commit.

Signed-off-by: Lars-Dominik Braun <lars@6xq.net>

guix/lint.scm

@@ -533,7 +533,8 @@ of a package, and INPUT-NAMES, a list of package specifications such as
   ;; Emit a warning if some inputs of PACKAGE are likely to should not be
   ;; an input at all.
   (let ((input-names '("python-setuptools"
-                       "python-pip")))
+                       "python-pip"
+                       "python-pre-commit")))
     (map (lambda (input)
            (make-warning
             package