Add mandatory build() to AKPBUILD

APKBUILD

@@ -10,6 +10,10 @@ license="GPL"
 depends="python3 py3-bcrypt py3-cffi py3-cryptography py3-dnspython py3-jinja2 py3-requests py3-six py3-werkzeug"
 options="!check !strip"
 
+build() {
+    return 0
+}
+
 package() {
     mkdir -p ${pkgdir}
     cp -rp etc ${pkgdir}