Add deprecation comment for profiler internals (#3167)

Author: sentrivana

sentry_sdk/profiler/__init__.py

@@ -22,7 +22,8 @@
 __all__ = [
     "start_profiler",
     "stop_profiler",
-    # Re-exported for backwards compatibility
+    # DEPRECATED: The following was re-exported for backwards compatibility. It
+    # will be removed from sentry_sdk.profiler in a future release.
     "MAX_PROFILE_DURATION_NS",
     "PROFILE_MINIMUM_SAMPLES",
     "Profile",