Bump run-script from 0.4.0-beta.256 to 0.4.0-beta.278

Author: xt0rted

.config/dotnet-tools.json

@@ -3,7 +3,7 @@
   "isRoot": true,
   "tools": {
     "run-script": {
-      "version": "0.4.0-beta.256",
+      "version": "0.4.0-beta.278",
       "commands": [
         "r"
       ]