[github] Change Ubuntu version to 22.04 #2079

Job	Run time
verilator	13s
tc-gcc	24s
check-opcodes	4s
check-control-registers	21s
riscv-isa-sim	9s
tc-llvm	55s
verilator-model (minpool)	6s
verilator-model (mempool)	8s
check-bootrom	10s
build-apps-gcc (minpool)	59s
build-apps-gcc (mempool)	55s
unit-test	2m 22s
tc-halide	8s
build-apps-llvm (minpool)	1m 17s
build-apps-llvm (mempool)	1m 12s
build-apps-halide (minpool)	1m 16s
build-apps-halide (mempool)	52s
run-apps-gcc	0s
run-apps-llvm	0s
run-apps-halide (minpool)	39s
run-apps-halide (mempool)	3m 6s
clean-up	4s
clean-up-compile-runs (minpool)	5s
clean-up-compile-runs (mempool)	5s
	15m 30s

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