[github] Change Ubuntu version to 22.04 #2073

Job	Run time
check-control-registers	20s
check-opcodes	3s
riscv-isa-sim	7s
tc-gcc	29s
tc-llvm	58s
verilator	7s
verilator-model (minpool)	5s
verilator-model (mempool)	6s
build-apps-gcc (minpool)	36s
check-bootrom	12s
unit-test	2m 4s
build-apps-gcc (mempool)	31s
build-apps-llvm (minpool)	1m 1s
tc-halide	11s
build-apps-llvm (mempool)	45s
run-apps-gcc	0s
build-apps-halide (minpool)	1m 33s
build-apps-halide (mempool)	1m 27s
run-apps-llvm	0s
run-apps-halide (minpool)	40s
run-apps-halide (mempool)	2m 55s
clean-up	3s
clean-up-compile-runs (minpool)	4s
clean-up-compile-runs (mempool)	6s
	14m 23s

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