refactor: missing token

Author: Andrew Seguin

src/material/core/tokens/m3/mat/_fab-small.scss

@@ -31,6 +31,7 @@ $prefix: (mat, fab-small);
     hover-container-elevation-shadow: map.get($systems, md-sys-elevation, level4),
     hover-state-layer-opacity: map.get($systems, md-sys-state, hover-state-layer-opacity),
     pressed-container-elevation-shadow: map.get($systems, md-sys-elevation, level3),
+    pressed-state-layer-opacity: map.get($systems, md-sys-state, pressed-state-layer-opacity),
   );
 
   $elevation-tokens: (