validateRestrictions was failing due to being unbound, fixed with arrow function

packages/@uppy/provider-views/src/ProviderView/ProviderView.js

@@ -556,7 +556,7 @@ module.exports = class ProviderView {
       pluginIcon: this.plugin.icon,
       i18n: this.plugin.uppy.i18n,
       uppyFiles: this.plugin.uppy.getFiles(),
-      validateRestrictions: this.plugin.uppy.validateRestrictions,
+      validateRestrictions: (...args) => this.plugin.uppy.validateRestrictions(...args),
     }
 
     return (