In order to prepare for the v6 release, we need to modify instances of v5 to v6 where they relate to the super linter package version

• https://github.com/super-linter/super-linter/blob/main/slim/README.md?plain=1#L5 Not needed anymore, see Move instructions from the wiki to docs #4957
• https://github.com/super-linter/super-linter/blob/main/docs/run-linter-locally.md?plain=1#L109 Not needed anymore, see Update documentation #4981
• https://github.com/super-linter/super-linter/blob/main/TEMPLATES/linter.yml#L60 Not needed anymore, see Update documentation #4981
• https://github.com/super-linter/super-linter/blob/main/slim/action.yml#L7
• https://github.com/super-linter/super-linter/blob/main/action.yml#L7
• https://github.com/super-linter/super-linter/blob/main/README.md?plain=1#L183