Picker font color fix (#8071)

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## Purpose
Fixed font color changing in pick selector

## Approach
Changed client ui styles

## References
DevExpress/testcafe-private#366

## Pre-Merge TODO
- [ ] Write tests for your proposed changes
- [ ] Make sure that existing tests do not fail

src/client/ui/styles.less

@@ -759,6 +759,7 @@
         flex-direction: column;
         background-color: white;
         box-shadow: 0px 0px 2px #8d8d8d;
+        color: black;
 
         .selector-value {
             height: 18px;