pv-migrate: remove extra v prefix from ldflags

`main.version` and `main.commit` were set to `v${version}` via ldflags.
However, version 3+ of pv-migrate prepends `v` internally when resolving
Kubernetes helper images, producing `vv3.3.0` instead of `v3.3.0`. Drop
the hardcoded `v` prefix from the ldflags so the software receives a
bare version string and constructs the image tag correctly. This also
aligns the behavior with goreleaser.

pkgs/by-name/pv/pv-migrate/package.nix

@@ -24,8 +24,8 @@ buildGoModule (finalAttrs: {
   ldflags = [
     "-s"
     "-w"
-    "-X main.version=v${finalAttrs.version}"
-    "-X main.commit=v${finalAttrs.version}"
+    "-X main.version=${finalAttrs.version}"
+    "-X main.commit=${finalAttrs.version}"
     "-X main.date=1970-01-01-00:00:01"
   ];