all: prepare for 1.0.0 release. (#26)

Update project for Zig 0.16 (#17)

* Update project for Zig 0.16

* Bump package version to 0.7.1

src: fast deinit feature. (#15)

* src: fast deinit feature.

don't traverse the tree in deinit(), if the memory can be freed on the allocator level.
useful for arena and fixed buffer allocators.

build.zig.zon: set version to 0.6.1.

build.zig.zon: update version to 0.6.0

src: add `tree.ascendAt`. (#9)

ascendAt returns an iterator pointing to the ith element.

src: add Tree.getOrEmplace to construct values in-place. (#8)

src: deleteAt now returns a KV pair. (#5)

* src: deleteAt now returns a KV pair.
src: fix some typos and improve comments.

* .github/workflows: use v2 of goto-bus-stop/setup-zig and zig v0.11.0.

README: add zig lang highlighting.