Remove unnecessary brackets from readme #521

Job	Run time
build (stellar-cli, stellar, ubuntu-20.04, x86_64-unknown-linux-gnu)	14m 28s
build (stellar-cli, stellar, ubuntu-20.04, aarch64-unknown-linux-gnu)	16m 47s
build (stellar-cli, stellar, macos-14, x86_64-apple-darwin)	10m 21s
build (stellar-cli, stellar, macos-12, aarch64-apple-darwin)	18m 23s
build (stellar-cli, stellar, windows-latest, x86_64-pc-windows-msvc, .exe)	21m 36s
build (soroban-cli, soroban, ubuntu-20.04, x86_64-unknown-linux-gnu)	15m 33s
build (soroban-cli, soroban, ubuntu-20.04, aarch64-unknown-linux-gnu)	18m 8s
build (soroban-cli, soroban, macos-14, x86_64-apple-darwin)	9m 37s
build (soroban-cli, soroban, macos-12, aarch64-apple-darwin)	16m 43s
build (soroban-cli, soroban, windows-latest, x86_64-pc-windows-msvc, .exe)	24m 20s
	2h 45m 56s

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