Add `ElectrumClient::server_features` method #1181

Job	Run time
Build and test macOS arm64 wheels (3.8)	7m 32s
Build and test macOS x86_64 wheels (3.8)	7m 8s
Build and test macOS arm64 wheels (3.9)	5m 25s
Build and test Manylinux 2.28 x86_64 wheels (cp38-cp38)	3m 53s
Build and test macOS x86_64 wheels (3.9)	9m 10s
Build and test macOS arm64 wheels (3.10)	7m 5s
Build and test Windows wheels (3.8)	6m 0s
Build and test Manylinux 2.28 x86_64 wheels (cp39-cp39)	3m 51s
Build and test macOS x86_64 wheels (3.10)	9m 0s
Build and test macOS arm64 wheels (3.11)	4m 34s
Build and test Windows wheels (3.9)	6m 4s
Build and test Manylinux 2.28 x86_64 wheels (cp310-cp310)	3m 48s
Build and test macOS x86_64 wheels (3.11)	6m 43s
Build and test macOS arm64 wheels (3.12)	6m 58s
Build and test Windows wheels (3.10)	5m 55s
Build and test Manylinux 2.28 x86_64 wheels (cp311-cp311)	3m 50s
Build and test macOS x86_64 wheels (3.12)	5m 3s
Build and test Windows wheels (3.11)	5m 55s
Build and test Manylinux 2.28 x86_64 wheels (cp312-cp312)	3m 49s
Build and test Windows wheels (3.12)	5m 37s
	1h 57m 20s

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