Use newer version of fabric.min.css

Author: millerds

src/taskpane/taskpane.html

@@ -14,7 +14,7 @@
     <script type="text/javascript" src="https://appsforoffice.microsoft.com/lib/1.1/hosted/office.js"></script>
 
     <!-- For more information on Fluent UI, visit https://developer.microsoft.com/fluentui#/. -->
-    <link rel="stylesheet" href="https://static2.sharepointonline.com/files/fabric/office-ui-fabric-core/9.6.1/css/fabric.min.css"/>
+    <link rel="stylesheet" href="https://static2.sharepointonline.com/files/fabric/office-ui-fabric-core/11.0.0/css/fabric.min.css"/>
 
     <!-- Template styles -->
     <link href="taskpane.css" rel="stylesheet" type="text/css" />

test/end-to-end/src/test-taskpane.html

@@ -14,7 +14,7 @@
     <script type="text/javascript" src="https://appsforoffice.microsoft.com/lib/beta/hosted/office.js"></script>
 
     <!-- For more information on Office UI Fabric, visit https://developer.microsoft.com/fabric. -->
-    <link rel="stylesheet" href="https://static2.sharepointonline.com/files/fabric/office-ui-fabric-core/9.6.1/css/fabric.min.css"/>
+    <link rel="stylesheet" href="https://static2.sharepointonline.com/files/fabric/office-ui-fabric-core/11.0.0/css/fabric.min.css"/>
 
     <!-- Template styles -->
     <link href="../../../src/taskpane/taskpane.css" rel="stylesheet" type="text/css" />