[github] Change Ubuntu version to 22.04 #2087

Job	Run time
verilator	10s
check-control-registers	20s
tc-gcc	30s
riscv-isa-sim	11s
tc-llvm	56s
check-opcodes	4s
verilator-model (minpool)	12s
verilator-model (mempool)	6s
build-apps-gcc (minpool)	1m 36s
check-bootrom	10s
build-apps-gcc (mempool)	1m 37s
unit-test	2m 1s
build-apps-llvm (minpool)	1m 28s
tc-halide	9s
build-apps-llvm (mempool)	1m 26s
build-apps-halide (minpool)	1m 20s
build-apps-halide (mempool)	54s
run-apps-gcc (minpool)	37s
run-apps-gcc (mempool)	2m 15s
run-apps-llvm (minpool)	30s
run-apps-llvm (mempool)	2m 24s
run-apps-halide (minpool)	38s
run-apps-halide (mempool)	2m 59s
clean-up	9s
clean-up-compile-runs (minpool)	3s
clean-up-compile-runs (mempool)	4s
	22m 49s

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