Use medium font weight in a few places (#8848)

* medium font toasts

* medium font tabs

* medium font trending pill

src/components/ProgressGuide/FollowDialog.tsx

@@ -539,7 +539,7 @@ let Tab = ({
             ]}>
             <Text
               style={[
-                /* TODO: medium weight */
+                a.font_medium,
                 active || hovered || pressed || focused
                   ? t.atoms.text
                   : t.atoms.text_contrast_medium,

src/components/Toast/Toast.tsx

@@ -92,7 +92,7 @@ export function ToastText({children}: {children: React.ReactNode}) {
       selectable={false}
       style={[
         a.text_md,
-        a.font_bold,
+        a.font_medium,
         a.leading_snug,
         a.pointer_events_none,
         {