style(nextcloud): cleanup unnecessary cast

Signed-off-by: Nikolas Rimikis <rimikis.nikolas@gmail.com>

packages/nextcloud/lib/src/client.dart

@@ -27,10 +27,7 @@ class NextcloudClient extends DynamiteClient {
     final String? userAgentOverride,
     super.cookieJar,
   }) : super(
-          baseHeaders: (<String, String?>{
+          baseHeaders: language != null ? {'Accept-Language': language} : null,
-            'Accept-Language': language,
-          }..removeWhere((final _, final value) => value == null))
-              .cast<String, String>(),
           userAgent: userAgentOverride ?? appType.userAgent,
           authentications: [
             if (appPassword != null) ...[

packages/nextcloud/lib/src/webdav/client.dart

@@ -103,8 +103,8 @@ class WebDavClient {
       'OPTIONS',
       _constructPath(),
     );
-    final davCapabilities = response.headers['dav']?.cast<String>().first ?? '';
+    final davCapabilities = response.headers['dav']?.first ?? '';
-    final davSearchCapabilities = response.headers['dasl']?.cast<String>().first ?? '';
+    final davSearchCapabilities = response.headers['dasl']?.first ?? '';
     return WebDavOptions(
       davCapabilities.split(',').map((final e) => e.trim()).where((final e) => e.isNotEmpty).toSet(),
       davSearchCapabilities.split(',').map((final e) => e.trim()).where((final e) => e.isNotEmpty).toSet(),