[github] Change Ubuntu version to 22.04 #2069

Job	Run time
riscv-isa-sim	7s
check-control-registers	21s
check-opcodes	4s
tc-gcc	29s
tc-llvm	50s
verilator	5s
verilator-model (minpool)	10s
verilator-model (mempool)	7s
check-bootrom	24s
build-apps-gcc (minpool)	28s
unit-test	2m 20s
build-apps-gcc (mempool)	28s
tc-halide	8s
build-apps-llvm (minpool)	45s
build-apps-llvm (mempool)	44s
build-apps-halide (minpool)	34s
build-apps-halide (mempool)	1m 10s
run-apps-gcc	0s
run-apps-llvm	0s
run-apps-halide (minpool)	31s
run-apps-halide (mempool)	3m 13s
clean-up	2s
clean-up-compile-runs (minpool)	2s
clean-up-compile-runs (mempool)	3s
	13m 5s

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