Optimize APK update checks and CI builds

packaging/alpine/local/lavinmq/APKBUILD

@@ -8,7 +8,7 @@ arch="x86_64"
 license="Apache-2.0"
 depends="ca-certificates /bin/sh"
 makedepends="
-	crystal>=1.20.1
+	crystal=1.21.0-r0
 	curl
 	gc-dev
 	help2man
@@ -40,6 +40,7 @@ export CRYSTAL_CACHE_DIR="${CRYSTAL_CACHE_DIR:-$srcdir/crystal-cache}"
 export SHARDS_CACHE_PATH="${SHARDS_CACHE_PATH:-$srcdir/shards-cache}"
 
 build() {
+	crystal --version
 	make
 	make man
 }