Remove man page date check

This doesn't work because actions/checkout uses a fetch depth of 1, so
every CI run acts as though man pages were made in the most recent
commit.

Additionally the VCS code uses committed date, so this check will fail
if any PR is made that changes man pages, but then is merged the
following day JST.

Author: jhawthorn

.github/workflows/check_misc.yml

@@ -82,11 +82,6 @@ jobs:
           fi
         continue-on-error: ${{ steps.now.outputs.mon < 12 }}
 
-      - name: Check if date in man pages is up-to-date
-        run: |
-          make V=1 GIT=git BASERUBY=ruby update-man-date
-          git diff --color --no-ext-diff --ignore-submodules --exit-code -- man
-
       - name: Check if to generate documents
         id: rdoc
         run: |