cleaned up and added missing "include" statements for pubkey.cpp and pubkey.h

removed comments next to include statements.

removed comments in include statements.

changed assert.h to cassert based on pr comments

src/pubkey.cpp

@@ -5,9 +5,16 @@
 
 #include <pubkey.h>
 
+#include <hash.h>
 #include <secp256k1.h>
+#include <secp256k1_extrakeys.h>
 #include <secp256k1_recovery.h>
 #include <secp256k1_schnorrsig.h>
+#include <span.h>
+#include <uint256.h>
+
+#include <algorithm>
+#include <cassert>
 
 namespace
 {