feat(ci): set pr-body-regex action input to *not* require commit body

[maze88]

As discussed with @e0ne , we wish to make commit message checking slightly less strict in PRs, i.e. to not enforce the commit message to have both a message and body; instead of only enforce a message.

Reference commit as example:

git commit -m "this is the commit *message* (which will be enforced)

this is the commit *body* (which shall become optional).
it's separeted from the message by a blank line, often contains details
over several more lines, and finally closed by the same opening quote
as the message."

This is achieved by changing the default behavior of the existing conventional-commit-checker action.

[coveralls]

Pull Request Test Coverage Report for Build 9017569994

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 21 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-0.02%) to 64.26%

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Files with Coverage Reduction	New Missed Lines	%
pkg/state/state_skel.go	2	84.82%
pkg/state/state_ipoib_network.go	8	75.24%
controllers/ipoibnetwork_controller.go	11	77.38%
<!--	Total:	21		-->

Totals
Change from base Build 9017372666:	-0.02%
Covered Lines:	3258
Relevant Lines:	5070

---

💛 - Coveralls