don't display the name input box for public groups as they can't be modified atm

ts/components/conversation/UpdateGroupNameDialog.tsx

@@ -99,18 +99,21 @@ export class UpdateGroupNameDialog extends React.Component<Props, State> {
         {this.renderAvatar()}
         <SpacerMD />
 
-        <input
-          type="text"
-          className="profile-name-input"
-          value={this.state.groupName}
-          placeholder={window.i18n('groupNamePlaceholder')}
-          onChange={this.onGroupNameChanged}
-          tabIndex={0}
-          required={true}
-          aria-required={true}
-          autoFocus={true}
-          disabled={!isAdmin}
-        />
+        {isAdmin ? (
+          <>
+            <input
+              type="text"
+              className="profile-name-input"
+              value={this.state.groupName}
+              placeholder={window.i18n('groupNamePlaceholder')}
+              onChange={this.onGroupNameChanged}
+              tabIndex={0}
+              required={true}
+              aria-required={true}
+              autoFocus={true}
+            />
+          </>
+        ) : null}
 
         <div className="session-modal__button-group">
           <SessionButton text={cancelText} onClick={this.closeDialog} />