rexiftool-v0.2.1

release(rexiftool): v0.2.1 — pick up nom-exif 3.4.1 GPS sub-IFD fix

Bumps the minimum nom-exif requirement from "3.4" to "3.4.1" so
`cargo install rexiftool --locked` and the pre-built GitHub Releases
binaries actually carry the Sony A7C2 HIF GPS fix (issue #50). Default
`cargo install rexiftool` would already pull 3.4.1 via the caret
range, but locked / binary installs were still serving 3.4.0.

Workflow tweak: pin `make_latest: "false"` on the rexiftool release
upload step so its tag never competes with the nom-exif lib tag for
the GitHub "Latest release" badge. (Today rexiftool-v0.2.0 wasn't
labelled Latest only because v3.4.0 outranks 0.2.0 in semver; future
rexiftool 1.x could accidentally promote itself.)