CI: Correct release script call to patch-em-all

[why]
The font matix contains the directory names of the font files. The
directory names are taken from
  bin/scripts/lib/fonts.json
and specifically extracted with
  bin/scripts/get-font-names-from-json.sho

That script returns the .folderNames

Later in the release script we use the folder name to limit the fonts
that patch-em-all shall process. Unfortunately patch-em-all could (until
the previous commit) just work with font-filenames and not with
directory names. But the matrix gives us just directory names.

This is for example a problem with this fonts:
$ ll src/unpatched-fonts/BigBlueTerminal
-rw-rw-r-- 1 fini fini 25632 Jan  1 14:03 BigBlue_Terminal_437TT.TTF
-rw-rw-r-- 1 fini fini 69964 Jan  1 14:03 BigBlue_TerminalPlus.TTF

The *directory* of that fonts is correctly noted in fonts.json as
"BigBlueTerminal" but the font files do not begin with that!

[how]
Now, that patch-em-all can also filter on the directory name, we just
need to utilized that in the workflow run. If the filter shall work on
directory names the first character needs to be a slash, so we just
prepend it to name we got from the matix.

Fixes: #824

Signed-off-by: Fini Jastrow <ulf.fini.jastrow@desy.de>

.github/workflows/release.yml

@@ -130,7 +130,7 @@ jobs:
         run: |
           cd -- "$GITHUB_WORKSPACE/bin/scripts"
           fontforge --script ../../font-patcher --version
-          ./gotta-patch-em-all-font-patcher\!.sh "${{ matrix.font }}"
+          ./gotta-patch-em-all-font-patcher\!.sh "/${{ matrix.font }}"
 
       - name: Generate fontconfig and casks
         run: |