change color for login input placeholder

packages/grafana-ui/src/themes/_variables.dark.scss.tmpl.ts

@@ -196,7 +196,7 @@ $input-border-color: $dark-6;
 $input-box-shadow: inset 1px 0px 4px 0px rgba(150, 150, 150, 0.1);
 $input-border-focus: $dark-6 !default;
 $input-box-shadow-focus: $blue-light !default;
-$input-color-placeholder: $gray-1 !default;
+$input-color-placeholder: $gray-2 !default;
 $input-label-bg: $gray-blue;
 $input-label-border-color: $dark-6;
 $input-color-select-arrow: $white;

public/sass/_variables.dark.generated.scss

@@ -199,7 +199,7 @@ $input-border-color: $dark-6;
 $input-box-shadow: inset 1px 0px 4px 0px rgba(150, 150, 150, 0.1);
 $input-border-focus: $dark-6 !default;
 $input-box-shadow-focus: $blue-light !default;
-$input-color-placeholder: $gray-1 !default;
+$input-color-placeholder: $gray-2 !default;
 $input-label-bg: $gray-blue;
 $input-label-border-color: $dark-6;
 $input-color-select-arrow: $white;