Add missing goto for checking encapsulation invariants.

When we encapsulate something with ML-KEM on OpenSSL, we were checking
that the amount written is what we expected, but a missing `goto` caused
it to be marked as a success.

This isn't really a reliability problem since we already know how much
encapsulation sizes are, we're just making sure OpenSSL and the managed
side agree on it.

Author: vcsjones

src/native/libs/System.Security.Cryptography.Native/pal_evp_kem.c

@@ -187,6 +187,7 @@ int32_t CryptoNative_EvpKemEncapsulate(EVP_PKEY* pKey,
             sharedSecretLengthT != Int32ToSizeT(sharedSecretLength))
         {
             ret = -1;
+            goto done;
         }
 
         ret = 1;