build: pin `@angular/` deps #61

Job	Run time
list	42s
workflow (build-cli)	1m 34s
workflow (modules-builder-tests)	2m 8s
workflow (devkit-core-tests)	1m 44s
workflow (devkit-core-tests-rerun)	1m 40s
workflow (build-unit-tests)	2m 0s
	9m 48s

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