Add placeholder parameter

The placeholder parameter tells Mojolicious how to parse the path. In
this case, Mojolicious will parse the path with relaxed placeholders,
which means parsing the path by slashes only. The default being
slashes and dots ([^/.]+) which isn't good for CPAN releases due to dots
in the version numbers.

Author: ssoriche

root/static/requests/cover.yml

@@ -14,6 +14,9 @@ cover:
           The name of the Release
         type: string
         required: true
+        # tell Mojolicious to use relaxed placeholders when
+        # parsing this parameter (dots are allowed)
+        x-mojo-placeholder: "#"
     responses:
       200:
         description: Release response