Accept absolute paths for 'global-json-file' input (#396)

src/setup-dotnet.ts

@@ -31,7 +31,7 @@ export async function run() {
 
     const globalJsonFileInput = core.getInput('global-json-file');
     if (globalJsonFileInput) {
-      const globalJsonPath = path.join(process.cwd(), globalJsonFileInput);
+      const globalJsonPath = path.resolve(process.cwd(), globalJsonFileInput);
       if (!fs.existsSync(globalJsonPath)) {
         throw new Error(
           `The specified global.json file '${globalJsonFileInput}' does not exist`