refactor(paxos): use `usize` for slot numbers (#1521) #903

Job	Run time
pre_job	7s
macos-universal (universal2-apple-darwin)	3m 33s
linux (x86_64-unknown-linux-gnu)	3m 31s
linux (i686-unknown-linux-gnu)	3m 32s
linux-cross (aarch64-unknown-linux-gnu, aarch64)	3m 31s
linux-cross (armv7-unknown-linux-gnueabihf, armv7)	3m 31s
windows (x86_64-pc-windows-msvc, x64)	3m 30s
windows (i686-pc-windows-msvc, x86)	3m 31s
windows (aarch64-pc-windows-msvc, x64)	3m 27s
Release	1s
	28m 14s

Provide feedback