Add Nix certificate path to ssl_certs.nim (#25763)

This makes it easier to run Nix built containers for Nim programs since
by default Nim doesn't search environment variables for SSL certs so its
a little annoying having to move around files

-
10e7ad5bbc/pkgs/by-name/ca/cacert/package.nix (L85)

lib/pure/ssl_certs.nim

@@ -36,6 +36,8 @@ elif defined(linux):
     # Android
     "/data/data/com.termux/files/usr/etc/tls/cert.pem",
     "/system/etc/security/cacerts",
+    # Nix
+    "/etc/ssl/certs/ca-bundle.crt"
   ]
 elif defined(bsd):
   const certificatePaths = [