[pre-commit] Update tclint to v6.0.1

[pre-commit] Update tclint to v6.0.1

Upstream tclint updated its stable release to v6.0.1.  That version includes
the pre-commit support that was missing in v0.6.0, which required us to use an
unofficial repo [1].

Update tclint to v6.0.1.

Tested by running:
...
$ pre-commit run --all-files tclint
tclint................................................................Passed
...

[1] commit 7f6c7a5bb37 ("[pre-commit] Add tclint hook")