Tweak the colours for API versionmodified information

These are now consistent across dark and light mode and uses slightly a
hue for `changed` that is further from the hue used for `added`.

src/furo/assets/styles/variables/_colors.scss

@@ -42,8 +42,8 @@
 
   --color-api-added: #21632c;
   --color-api-added-border: #38a84d;
-  --color-api-changed: #09635b;
-  --color-api-changed-border: #0ea498;
+  --color-api-changed: #046172;
+  --color-api-changed-border: #06a1bc;
   --color-api-deprecated: #605706;
   --color-api-deprecated-border: #f0d90f;
   --color-api-removed: #b30000;
@@ -179,12 +179,12 @@
 
   --color-api-added: #3db854;
   --color-api-added-border: #267334;
-  --color-api-changed: #b1a10b;
-  --color-api-changed-border: #6e6407;
-  --color-api-deprecated: #ff7575;
-  --color-api-deprecated-border: #c70000;
+  --color-api-changed: #09b0ce;
+  --color-api-changed-border: #056d80;
+  --color-api-deprecated: #b1a10b;
+  --color-api-deprecated-border: #6e6407;
   --color-api-removed: #ff7575;
-  --color-api-removed-border: #c70000;
+  --color-api-removed-border: #b03b3b;
 
   // Admonitions
   --color-admonition-background: #18181a;