Add missing to_type_hint to WindowedValueCoder #28570

Job	Run time
Check GCP variables	14s
Python Unit Tests (macos-latest, 3.9, py39)	20m 27s
Python Unit Tests (macos-latest, 3.10, py310)	14m 58s
Python Wordcount Direct Runner (self-hosted, ubuntu-20.04, main, 3.9)	5m 51s
Python Unit Tests (macos-latest, 3.11, py311)	17m 31s
Python Wordcount Direct Runner (self-hosted, ubuntu-20.04, main, 3.10)	7m 54s
Python Unit Tests (macos-latest, 3.12, py312)	13m 55s
Python Wordcount Direct Runner (self-hosted, ubuntu-20.04, main, 3.11)	7m 19s
Python Unit Tests (windows-latest, 3.9, py39)	14m 45s
Python Unit Tests (windows-latest, 3.10, py310)	14m 36s
Python Wordcount Direct Runner (self-hosted, ubuntu-20.04, main, 3.12)	6m 22s
Python Unit Tests (windows-latest, 3.11, py311)	15m 42s
Python Wordcount Direct Runner (macos-latest, 3.9)	3m 32s
Python Unit Tests (windows-latest, 3.12, py312)	14m 48s
Python Wordcount Direct Runner (macos-latest, 3.10)	5m 3s
Python Wordcount Direct Runner (macos-latest, 3.11)	3m 17s
Python Wordcount Direct Runner (macos-latest, 3.12)	5m 58s
Python Wordcount Direct Runner (windows-latest, 3.9)	3m 22s
Python Wordcount Direct Runner (windows-latest, 3.10)	3m 33s
Python Wordcount Direct Runner (windows-latest, 3.11)	3m 34s
Python Wordcount Direct Runner (windows-latest, 3.12)	3m 22s
Build python source distribution	0s
Python Wordcount Dataflow	0s
	3h 6m 3s

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