Update JS dependencies and misc tweaks (#25540)

- Update all JS dependencies
- Enable `declaration-property-unit-disallowed-list` to forbid `em` on
`line-height`
- Rename dependency update targets to `update-js` and `update-py` and
document them
- Remove margin on Asciicast viewer
- Tested Swagger, Katex, Asciicast

<img width="1243" alt="Screenshot 2023-06-27 at 19 51 05"
src="https://github.com/go-gitea/gitea/assets/115237/2d2722a0-2aa7-4f4c-b8bd-17e1f3637b78">

.stylelintrc.yaml

@@ -50,7 +50,7 @@ rules:
   declaration-no-important: null
   declaration-property-max-values: null
   declaration-property-unit-allowed-list: null
-  declaration-property-unit-disallowed-list: null
+  declaration-property-unit-disallowed-list: {line-height: [em]}
   declaration-property-value-allowed-list: null
   declaration-property-value-disallowed-list: null
   declaration-property-value-no-unknown: true