Hide danger-local-https feature with _ prefix

[DanGould]

This prevents it from showing up in docs.rs documentation

[coveralls]

Pull Request Test Coverage Report for Build 12128875459

Details

• 1 of 5 (20.0%) changed or added relevant lines in 3 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.05%) to 61.516%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
payjoin-cli/src/app/v1.rs	0	2	0.0%
payjoin-cli/src/app/v2.rs	0	2	0.0%

Files with Coverage Reduction	New Missed Lines	%
payjoin/src/send/mod.rs	2	92.78%

Totals
Change from base Build 12086002692:	-0.05%
Covered Lines:	2791
Relevant Lines:	4537

---

💛 - Coveralls

[nothingmuch]

• 1 of 5 (20.0%) changed or added relevant lines in 3 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.05%) to 61.516%

[nothingmuch]

ACK, coverall's "changed" lines are noise and presumably an analysis bug on their side? not sure what's going on there but the "new" lines clearly existed before, and unchanged the "lost coverage" lines are just attrs

manually verified that git grep '[^_]danger-local-https' has no matches as expected