Automated change: Fix sanity tests

src/core/lib/security/credentials/external/external_account_credentials.cc

diff --git a/src/core/lib/security/credentials/external/external_account_credentials.cc b/src/core/lib/security/credentials/external/external_account_credentials.cc
index 5244d41..3ffd2ac 100644
--- a/src/core/lib/security/credentials/external/external_account_credentials.cc
+++ b/src/core/lib/security/credentials/external/external_account_credentials.cc
@@ -54,7 +54,6 @@
 #include "src/core/lib/security/credentials/external/file_external_account_credentials.h"
 #include "src/core/lib/security/credentials/external/url_external_account_credentials.h"
 #include "src/core/lib/security/util/json_util.h"
-#include "src/core/lib/slice/b64.h"
 #include "src/core/lib/uri/uri_parser.h"
 
 #define EXTERNAL_ACCOUNT_CREDENTIALS_GRANT_TYPE \