fix(package): update npm files field for new server bundle (#639)

Closes #637

Author: delucis

package.json

@@ -40,7 +40,6 @@
     "dist/boardgameio.js",
     "dist/boardgameio.min.js",
     "dist/boardgameio.es.js",
-    "dist/server.js",
     "dist/esm",
     "dist/cjs",
     "dist/types",
@@ -49,7 +48,7 @@
     "debug",
     "react",
     "react-native",
-    "server.js",
+    "server",
     "ai",
     "plugins",
     "master",