Ensure audio icon on tab is vertically centered (it only seemed to be…

… a problem on Windows, > 100% DPI) (#7854)

Fixes #7815

Auditors: @cezaraugusto, @srirambv

Test Plan:
1. Be on a Windows machine which is set at 125% DPI
2. Launch Brave and visit youtube.com
3. Click the first link you see and let the video play
4. Ensure you're at a # of tabs where audio icon is showing (if not, close some tabs)
5. Audio icon should look vertically centered now

app/renderer/components/tabContent.js

@@ -290,7 +290,8 @@ const styles = StyleSheet.create({
   },
 
   audioIcon: {
-    color: globalStyles.color.highlightBlue
+    color: globalStyles.color.highlightBlue,
+    fontSize: '16px'
   },
 
   newSession: {