fix(symbolize): use correct format specifier (#1056)

diff --git a/src/symbolize.cc b/src/symbolize.cc
index 5c78be5..09bc9eb 100644
--- a/src/symbolize.cc
+++ b/src/symbolize.cc
@@ -943,7 +943,7 @@
       const std::size_t suffixlen = fnlen + extralen + fnlen + digits;
 
       if (suffixlen < out_size) {
-        out_size -= std::snprintf(out + namelen, out_size, " (%s:%u)",
+        out_size -= std::snprintf(out + namelen, out_size, " (%s:%lu)",
                                   line.FileName, line.LineNumber);
       }
     }