packit: update dist_git_branches to target fedora-all #2528

Job	Run time
Tests, stable toolchain (x86_64)	2m 21s
Tests, stable toolchain (s390x)	13m 27s
Lints, pinned toolchain (x86_64)	1m 18s
Docs	7m 10s
Lints, pinned toolchain (s390x)	9m 23s
Tests, minimum supported toolchain (x86_64)	2m 26s
Tests, minimum supported toolchain (s390x)	14m 7s
Tests, unstable toolchain (beta, x86_64)	2m 12s
Tests, unstable toolchain (nightly, x86_64)	2m 26s
	54m 50s

Provide feedback