add type hint for `Minio.get_object` #107

Job	Run time
Test on python 3.7 and ubuntu-latest	3m 18s
Test on python 3.7 and windows-latest	3m 21s
Test on python 3.7 and macos-latest	23s
Test on python 3.8 and ubuntu-latest	1m 59s
Test on python 3.8 and windows-latest	2m 38s
Test on python 3.8 and macos-latest	21s
Test on python 3.9 and ubuntu-latest	2m 19s
Test on python 3.9 and windows-latest	2m 41s
Test on python 3.9 and macos-latest	18s
Test on python 3.10 and ubuntu-latest	2m 18s
Test on python 3.10 and windows-latest	3m 15s
Test on python 3.10 and macos-latest	24s
Test on python 3.11 and ubuntu-latest	1m 37s
Test on python 3.11 and windows-latest	3m 2s
Test on python 3.11 and macos-latest	19s
	28m 13s

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