Migrate license to AGPL - Update license in the ide settings.

.idea/copyright/Element_FOSS.xml

@@ -1,6 +1,6 @@
 <component name="CopyrightManager">
   <copyright>
-    <option name="notice" value="Copyright (c) &amp;#36;today.year New Vector Ltd&#10;&#10;Licensed under the Apache License, Version 2.0 (the &quot;License&quot;);&#10;you may not use this file except in compliance with the License.&#10;You may obtain a copy of the License at&#10;&#10;    https://www.apache.org/licenses/LICENSE-2.0&#10;&#10;Unless required by applicable law or agreed to in writing, software&#10;distributed under the License is distributed on an &quot;AS IS&quot; BASIS,&#10;WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.&#10;See the License for the specific language governing permissions and&#10;limitations under the License." />
+    <option name="notice" value="Copyright &amp;#36;today.year New Vector Ltd.&#10;&#10;SPDX-License-Identifier: AGPL-3.0-only&#10;Please see LICENSE in the repository root for full details." />
     <option name="myName" value="Element FOSS" />
   </copyright>
-</component>
+</component>