Fix [Cran] devtools license (#6515)

services/cran/cran.service.js

@@ -26,7 +26,7 @@ class CranLicense extends BaseCranService {
     {
       title: 'CRAN/METACRAN',
       namedParams: { packageName: 'devtools' },
-      staticPreview: this.render({ license: 'GPL (>= 2)' }),
+      staticPreview: this.render({ license: 'MIT + file LICENSE' }),
     },
   ]
 

services/cran/cran.tester.js

@@ -19,7 +19,7 @@ t.create('version (not found)')
 
 t.create('license (valid)')
   .get('/l/devtools.json')
-  .expectBadge({ label: 'license', message: 'GPL (>= 2)' })
+  .expectBadge({ label: 'license', message: 'MIT + file LICENSE' })
 
 t.create('license (not found)')
   .get('/l/some-bogus-package.json')