MISC: skip CI for commits that do not modify core sources.

[cebarobot]

For a long time, modifying files which do not affect CPU core still have to run and pass all CI processes, which could waste a lot of time. This patch introduces dorny/paths-filter@v3 to skip some commits which only modifies edge files such as issue templates, codeowners and readme.

[ngc7331]

Maybe a path filter could serve the same purpose without requiring a separate "change detection" task?
https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#onpushpull_requestpull_request_targetpathspaths-ignore

[cebarobot]

Maybe a path filter could serve the same purpose without requiring a separate "change detection" task? https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#onpushpull_requestpull_request_targetpathspaths-ignore

This won't work in our case. See this Handling skipped but required checks.

Warning: If a workflow is skipped due to path filtering, branch filtering or a commit message, then checks associated with that workflow will remain in a "Pending" state. A pull request that requires those checks to be successful will be blocked from merging.

[XiangShanRobot]

[Generated by IPC robot]
commit: fa33ed2

commit	astar	copy_and_run	coremark	gcc	gromacs	lbm	linux	mcf	microbench	milc	namd	povray	wrf	xalancbmk
fa33ed2	1.808	0.447	2.043	1.187	2.938	2.508	2.291	0.921	1.369	1.441	3.454	2.658	2.399	2.932

master branch:

commit	astar	copy_and_run	coremark	gcc	gromacs	lbm	linux	mcf	microbench	milc	namd	povray	wrf	xalancbmk
a7828dc	1.808		2.043	1.187	2.938	2.508		0.921	1.369	1.441	3.454		2.399	2.932
9f598f8
e975de6	1.808	0.447	2.043	1.187	2.938	2.508	2.291	0.921	1.369	1.441	3.454	2.658	2.399	2.932
ff9b84b		0.447	2.043	1.187			2.291	0.921	1.369		3.454	2.658		2.932
3bec463	1.808	0.447	2.043	1.187	2.938	2.508	2.291	0.921	1.369	1.441	3.454	2.658	2.399	2.932
2d12882		0.447	2.043	1.187			2.291	0.921	1.369		3.454	2.658		2.932
ef14270	1.827	0.448	2.048	1.190	2.938	2.508	2.289	0.932	1.369	1.410	3.445	2.672	2.398	2.932
5c5f442	1.827	0.448	2.048	1.190	2.938	2.508	2.289	0.932	1.369	1.410	3.445	2.672	2.398	2.932
d67c873	1.827	0.448	2.048	1.190	2.938	2.508	2.289	0.932	1.369	1.410	3.445	2.672	2.398	2.932