composer.json: Move knplabs/github-api to require

Part of #1158

Author: reedy

composer.json

@@ -10,10 +10,10 @@
         "ext-json": "*",
         "ext-mbstring": "*",
         "ext-pdo": "*",
-        "ext-simplexml": "*"
+        "ext-simplexml": "*",
+        "knplabs/github-api": "^1.4"
     },
     "require-dev": {
-        "knplabs/github-api": "^1.4",
         "php-parallel-lint/php-parallel-lint": "^1.3.2",
         "simpletest/simpletest": "^1.1"
     },