Auto merge of #115700 - GuillaumeGomez:migrate-gui-test-color-39, r=notriddle

Migrate GUI colors test to original CSS color format

Follow-up of #111459.

r? `@notriddle`

Author: bors

tests/rustdoc-gui/help-page.goml

@@ -33,21 +33,21 @@ define-function: (
 
 call-function: ("check-colors", {
     "theme": "ayu",
-    "color": "rgb(197, 197, 197)",
-    "background": "rgb(49, 69, 89)",
-    "box_shadow": "rgb(92, 103, 115)",
+    "color": "#c5c5c5",
+    "background": "#314559",
+    "box_shadow": "#5c6773",
 })
 call-function: ("check-colors", {
     "theme": "dark",
-    "color": "rgb(0, 0, 0)",
-    "background": "rgb(250, 251, 252)",
-    "box_shadow": "rgb(198, 203, 209)",
+    "color": "#000",
+    "background": "#fafbfc",
+    "box_shadow": "#c6cbd1",
 })
 call-function: ("check-colors", {
     "theme": "light",
-    "color": "rgb(0, 0, 0)",
-    "background": "rgb(250, 251, 252)",
-    "box_shadow": "rgb(198, 203, 209)",
+    "color": "#000",
+    "background": "#fafbfc",
+    "box_shadow": "#c6cbd1",
 })
 
 // This test ensures that opening the help popover without switching pages works.