Switch from `x86_64-sun-solaris` to `x86_64-pc-solaris` #3

Job	Run time
Test (ubuntu-latest, stable)	13s
Rustfmt	10s
Test (ubuntu-latest, beta)	18s
Test (ubuntu-latest, nightly)	22s
Test (macos-latest, stable)	21s
Test (macos-latest, beta)	24s
Test (macos-latest, nightly)	23s
Test (windows-latest, stable)	1m 31s
Test (windows-latest, beta)	1m 20s
Test (windows-latest, nightly)	1m 20s
Test Cross Compile - aarch64-apple-ios	18s
Test Cross Compile - aarch64-unknown-linux-gnu	28s
Test Cross Compile - arm-unknown-linux-gnueabihf	30s
Test Cross Compile - powerpc-unknown-linux-gnu	42s
Test Cross Compile - s390x-unknown-linux-gnu	50s
Test Cross Compile - x86_64-unknown-linux-musl	36s
Test Cross Compile - aarch64-unknown-linux-musl	40s
Test Cross Compile - x86_64-pc-windows-gnu	57s
Test Cross Compile - x86_64-unknown-freebsd	30s
Test Cross Compile - x86_64-unknown-netbsd	31s
Test Cross Compile - x86_64-pc-solaris	16s
Test Cross Compile - x86_64-unknown-illumos	39s
	13m 19s

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