Do not export GOROOT

This has not been necessary since [Go 1.9](https://go.dev/doc/go1.9#goroot) at
least (although clunky to do so then) but definitely not since
[Go 1.10](https://go.dev/doc/go1.10#goroot).

This is cargo culting code that is more than 2 years out of date and runs into
issues when multiple go versions are used in an action run.

Signed-off-by: Manuel Mendez <mmendez534@gmail.com>

Author: mmlb

__tests__/setup-go.test.ts

@@ -231,7 +231,7 @@ describe('setup-go', () => {
     expect(logSpy).toHaveBeenCalledWith(`Setup go version spec 1.13.0`);
   });
 
-  it('exports GOROOT', async () => {
+  it('does not export any varibles', async () => {
     inputs['go-version'] = '1.13.0';
     inSpy.mockImplementation(name => inputs[name]);
 
@@ -244,7 +244,7 @@ describe('setup-go', () => {
     });
 
     await main.run();
-    expect(vars).toBe({GOROOT: 'foo'});
+    expect(vars).toStrictEqual({});
   });
 
   it('finds a version of go already in the cache', async () => {

dist/index.js

@@ -2080,7 +2080,6 @@ function run() {
                 let auth = !token || isGhes() ? undefined : `token ${token}`;
                 const checkLatest = core.getBooleanInput('check-latest');
                 const installDir = yield installer.getGo(versionSpec, checkLatest, auth);
-                core.exportVariable('GOROOT', installDir);
                 core.addPath(path_1.default.join(installDir, 'bin'));
                 core.info('Added go to the path');
                 let added = yield addBinToPath();

src/main.ts

@@ -23,7 +23,6 @@ export async function run() {
       const checkLatest = core.getBooleanInput('check-latest');
       const installDir = await installer.getGo(versionSpec, checkLatest, auth);
 
-      core.exportVariable('GOROOT', installDir);
       core.addPath(path.join(installDir, 'bin'));
       core.info('Added go to the path');