Drop libnsl-dev build-dependency

Colin Watsonrequested to merge
cjwatson/python3:drop-libnsl-dev-3.14 into python3.14

This was added in Python 3.12 to fix https://bugs.debian.org/1065128. However, it's superfluous in Python 3.13 since the nis module was dropped as one of the "dead batteries" (https://peps.python.org/pep-0594/#nis).

(Equivalent of !38 (merged), but for 3.14.)

Merge request reports