Quote filename in error message

Project standard is to quote filenames in error and log messages, which
commit 2da74d8d64 missed in two error messages.

Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Reported-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Discussion: https://postgr.es/m/20250404.120328.103562371975971823.horikyota.ntt@gmail.com

src/interfaces/libpq/fe-secure-openssl.c

@@ -711,7 +711,7 @@ SSL_CTX_keylog_cb(const SSL *ssl, const char *line)
 
 	if (fd == -1)
 	{
-		libpq_append_conn_error(conn, "could not open ssl keylog file %s: %s",
+		libpq_append_conn_error(conn, "could not open ssl keylog file \"%s\": %s",
 								conn->sslkeylogfile, pg_strerror(errno));
 		return;
 	}
@@ -719,7 +719,7 @@ SSL_CTX_keylog_cb(const SSL *ssl, const char *line)
 	/* line is guaranteed by OpenSSL to be NUL terminated */
 	rc = write(fd, line, strlen(line));
 	if (rc < 0)
-		libpq_append_conn_error(conn, "could not write to ssl keylog file %s: %s",
+		libpq_append_conn_error(conn, "could not write to ssl keylog file \"%s\": %s",
 								conn->sslkeylogfile, pg_strerror(errno));
 	else
 		rc = write(fd, "\n", 1);