Add `ictce/5.3.0` too. 

We usually don't add them, because we don't really use `ictce/5.3.0` as a production toolchain yet on our end. We've had one too many bad experiences with new major versions of Intel compilers, I'd rather wait for a couple more v13.x releases of icc/ifort.

No `source_urls` is out of my hands, sorry.

Any other remarks w.r.t. this PR? Good to go?