chore(profiling): add import typing (#15520)

## Description

Fix broken main 
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## Testing

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## Risks

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Author: taegyunkim

ddtrace/profiling/collector/threading.py

@@ -1,6 +1,7 @@
 from __future__ import absolute_import
 
 import threading
+import typing
 
 from ddtrace.internal._unpatched import _threading as ddtrace_threading
 from ddtrace.internal.datadog.profiling import stack_v2