[CollapsingToolbarLayout] Fix text shadow fading when transitioning between expanded and collapsed states

Resolves #3641

GIT_ORIGIN_REV_ID=7243f7a2f09b04caceec488443b1652a8ffef961
PiperOrigin-RevId: 578838845

Author: pubiqq

lib/java/com/google/android/material/internal/CollapsingTextHelper.java

@@ -672,6 +672,14 @@ private void calculateOffsets(final float fraction) {
       int textAlpha = (int) (calculateFadeModeTextAlpha(fraction) * originalAlpha);
 
       textPaint.setAlpha(textAlpha);
+      // Workaround for API 31(+). Applying the shadow color for the painted text.
+      if (VERSION.SDK_INT >= VERSION_CODES.S) {
+        textPaint.setShadowLayer(
+            currentShadowRadius,
+            currentShadowDx,
+            currentShadowDy,
+            MaterialColors.compositeARGBWithAlpha(currentShadowColor, textPaint.getAlpha()));
+      }
     }
 
     ViewCompat.postInvalidateOnAnimation(view);