testing/b3sum: run cargo install with --locked

testing/b3sum/APKBUILD

@@ -2,7 +2,7 @@
 # Maintainer:
 pkgname=b3sum
 pkgver=1.0.0
-pkgrel=0
+pkgrel=1
 pkgdesc="Command line implementation of the BLAKE3 hash function"
 url="https://blake3.io"
 arch="all !s390x !armhf !mips !mips64 !riscv64" # armhf: 'vaddq_u32': target specific option mismatch
@@ -23,7 +23,7 @@ check() {
 }
 
 package() {
-	cargo install --path . --root="$pkgdir/usr" --no-default-features ${_features:+--features "$_features"}
+	cargo install --locked --path . --root="$pkgdir/usr" --no-default-features ${_features:+--features "$_features"}
 	rm "$pkgdir"/usr/.crates*
 }