Label PRs to python/core/api also.

Fix sparsity labeling.

PiperOrigin-RevId: 324313809

Author: alanchiao

.github/labeler.yml

@@ -14,15 +14,22 @@
 
 technique:clustering:
 - tensorflow_model_optimization/python/core/clustering/**/*
+- tensorflow_model_optimization/python/core/api/clustering/**/*
 - tensorflow_model_optimization/python/examples/clustering/**/*
 - tensorflow_model_optimization/g3doc/guide/clustering/**/*
 
 technique:pruning:
 - tensorflow_model_optimization/python/core/pruning/**/*
-- tensorflow_model_optimization/python/examples/pruning/**/
-- tensorflow_model_optimization/g3doc/guide/pruning/**/
+- tensorflow_model_optimization/python/core/api/pruning/**/*
+- tensorflow_model_optimization/python/examples/pruning/**/*
+- tensorflow_model_optimization/g3doc/guide/pruning/**/*
 
 technique:qat:
 - tensorflow_model_optimization/python/core/quantization/**/*
+- tensorflow_model_optimization/python/core/api/quantization/**/*
 - tensorflow_model_optimization/python/examples/quantization/**/*
 - tensorflow_model_optimization/g3doc/guide/quantization/**/*
+
+# Note: this does not capture all PRs that need a API review.
+api-review:
+- tensorflow_model_optimization/python/core/api/**/*