Bump ex_doc from 0.34.2 to 0.35.1 #82

Job	Run time
NIF 2.16 - arm-unknown-linux-gnueabihf (ubuntu-20.04)	1m 36s
NIF 2.16 - aarch64-unknown-linux-gnu (ubuntu-20.04)	1m 30s
NIF 2.16 - aarch64-unknown-linux-musl (ubuntu-20.04)	1m 42s
NIF 2.16 - aarch64-apple-darwin (macos-latest)	1m 19s
NIF 2.16 - riscv64gc-unknown-linux-gnu (ubuntu-20.04)	1m 25s
NIF 2.16 - x86_64-apple-darwin (macos-latest)	1m 18s
NIF 2.16 - x86_64-unknown-linux-gnu (ubuntu-20.04)	1m 14s
NIF 2.16 - x86_64-unknown-linux-musl (ubuntu-20.04)	1m 35s
NIF 2.16 - x86_64-pc-windows-gnu (windows-2019)	2m 53s
NIF 2.16 - x86_64-pc-windows-msvc (windows-2019)	2m 30s
NIF 2.15 - arm-unknown-linux-gnueabihf (ubuntu-20.04)	1m 34s
NIF 2.15 - aarch64-unknown-linux-gnu (ubuntu-20.04)	1m 32s
NIF 2.15 - aarch64-unknown-linux-musl (ubuntu-20.04)	1m 40s
NIF 2.15 - aarch64-apple-darwin (macos-latest)	1m 11s
NIF 2.15 - riscv64gc-unknown-linux-gnu (ubuntu-20.04)	1m 25s
NIF 2.15 - x86_64-apple-darwin (macos-latest)	1m 16s
NIF 2.15 - x86_64-unknown-linux-gnu (ubuntu-20.04)	1m 9s
NIF 2.15 - x86_64-unknown-linux-musl (ubuntu-20.04)	1m 40s
NIF 2.15 - x86_64-pc-windows-gnu (windows-2019)	3m 10s
NIF 2.15 - x86_64-pc-windows-msvc (windows-2019)	2m 28s
	34m 7s

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