Adwaita: explicitelly set label caret-color to currentColor

since it doesn't always inherit 'color' color as it should.

gtk/theme/Adwaita/_common.scss

@@ -144,6 +144,8 @@ flowbox {
 }
 
 label {
+  caret-color: currentColor; // this shouldn't be needed.
+
   &.separator {
     @extend .dim-label;
 

gtk/theme/Adwaita/gtk-contained-dark.css

@@ -90,19 +90,21 @@ flowbox flowboxchild {
   flowbox flowboxchild:selected {
     outline-offset: -2px; }
 
-label.separator {
-  color: #eeeeec; }
-  label.separator:backdrop {
+label {
+  caret-color: currentColor; }
+  label.separator {
+    color: #eeeeec; }
+    label.separator:backdrop {
+      color: #919494; }
+  label selection {
+    background-color: #215d9c;
+    color: #ffffff; }
+  label:disabled {
+    color: #919494; }
+    label:disabled:backdrop {
+      color: #566164; }
+  label:backdrop {
     color: #919494; }
-label selection {
-  background-color: #215d9c;
-  color: #ffffff; }
-label:disabled {
-  color: #919494; }
-  label:disabled:backdrop {
-    color: #566164; }
-label:backdrop {
-  color: #919494; }
 
 .dim-label, label.separator, .titlebar:not(headerbar) .subtitle,
 headerbar .subtitle {

gtk/theme/Adwaita/gtk-contained.css

@@ -90,19 +90,21 @@ flowbox flowboxchild {
   flowbox flowboxchild:selected {
     outline-offset: -2px; }
 
-label.separator {
-  color: #2e3436; }
-  label.separator:backdrop {
+label {
+  caret-color: currentColor; }
+  label.separator {
+    color: #2e3436; }
+    label.separator:backdrop {
+      color: #8b8e8f; }
+  label selection {
+    background-color: #4a90d9;
+    color: #ffffff; }
+  label:disabled {
+    color: #8b8e8f; }
+    label:disabled:backdrop {
+      color: #c3c3c0; }
+  label:backdrop {
     color: #8b8e8f; }
-label selection {
-  background-color: #4a90d9;
-  color: #ffffff; }
-label:disabled {
-  color: #8b8e8f; }
-  label:disabled:backdrop {
-    color: #c3c3c0; }
-label:backdrop {
-  color: #8b8e8f; }
 
 .dim-label, label.separator, .titlebar:not(headerbar) .subtitle,
 headerbar .subtitle {