Remove unused include in now public header

Change-Id: I907932b04547c4cc779ec4e1edbebf2b12162ffa
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/66247
Auto-Submit: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: Adam Langley <agl@google.com>
Commit-Queue: David Benjamin <davidben@google.com>

include/openssl/pki/certificate.h

diff --git a/include/openssl/pki/certificate.h b/include/openssl/pki/certificate.h
index 7d41d64..3adaa03 100644
--- a/include/openssl/pki/certificate.h
+++ b/include/openssl/pki/certificate.h
@@ -18,7 +18,6 @@
 #include <memory>
 #include <string>
 #include <string_view>
-#include <vector>
 
 #include <openssl/base.h>
 #include <openssl/span.h>