Add new stylelint rules

These rules were added in stylelint 16.13.0 and IMHO can be usefull check
this rules.

Note that we are add a new rule value in override section because we are
receiving an error for font-url like:
> Unexpected unknown value "font-url("icons.eot")"

.stylelintrc.yml

@@ -9,9 +9,13 @@ plugins:
   - stylelint-scss
   - "@stylistic/stylelint-plugin"
 rules:
+  at-rule-descriptor-no-unknown: true
+  at-rule-descriptor-value-no-unknown: true
   at-rule-disallowed-list:
     - debug
+  at-rule-no-deprecated: true
   at-rule-no-vendor-prefix: true
+  at-rule-prelude-no-invalid: true
   block-no-empty: true
   color-hex-length: "short"
   color-named: "never"
@@ -92,6 +96,9 @@ rules:
   "@stylistic/number-leading-zero": "always"
   "@stylistic/selector-list-comma-newline-after": always
 overrides:
+  - files: app/assets/stylesheets/icons.scss
+    rules:
+      at-rule-descriptor-value-no-unknown: null
   - files: app/assets/stylesheets/legislation_process.scss
     rules:
       max-nesting-depth: 8