Add typing in signer.py #242

Job	Run time
Test on python 3.7 and ubuntu-latest	2m 9s
Test on python 3.7 and windows-latest	2m 46s
Test on python 3.7 and macos-latest	31s
Test on python 3.8 and ubuntu-latest	1m 45s
Test on python 3.8 and windows-latest	2m 37s
Test on python 3.8 and macos-latest	20s
Test on python 3.9 and ubuntu-latest	1m 43s
Test on python 3.9 and windows-latest	2m 25s
Test on python 3.9 and macos-latest	35s
Test on python 3.10 and ubuntu-latest	1m 59s
Test on python 3.10 and windows-latest	2m 23s
Test on python 3.10 and macos-latest	17s
Test on python 3.11 and ubuntu-latest	1m 29s
Test on python 3.11 and windows-latest	2m 39s
Test on python 3.11 and macos-latest	18s
Test on python 3.12 and ubuntu-latest	1m 41s
Test on python 3.12 and windows-latest	2m 7s
Test on python 3.12 and macos-latest	23s
	28m 7s

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