Deprecation warnings

[dylan-asmar]

tectonic() and pdftocairo() appear to be deprecated.

When running test:

┌ Warning: tectonic() is deprecated, use the non-do-block form
│   caller = ip:0x0
└ @ Core :-1
...
┌ Warning: pdftocairo() is deprecated, use the non-do-block form
│   caller = ip:0x0
└ @ Core :-1