acvptool: Fix typo hard-coding the HTTP method.

Change-Id: I134e2e8d73913843d21d8a3d7f2b266bee6ba73b
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/46964
Reviewed-by: Adam Langley <agl@google.com>

util/fipstools/acvp/acvptool/acvp/acvp.go

@@ -422,7 +422,7 @@ func (server *Server) write(method string, reply interface{}, endPoint string, c
 	buf.Write(contents)
 	buf.WriteString(requestSuffix)
 
-	req, err := server.newRequestWithToken("POST", endPoint, &buf)
+	req, err := server.newRequestWithToken(method, endPoint, &buf)
 	if err != nil {
 		return err
 	}