Release rstml 0.13.1 and rstml-control-flow 0.2.1 #71

Would you be able to publish patch releases of rstml and
rstml-control-flow containing #70?

#70 removes syn_derive and the transitive proc-macro-error2 /
proc-macro-error-attr2 dependencies to address RUSTSEC-2026-0173.
The currently published versions (rstml 0.13.0 and
rstml-control-flow 0.2.0) still contain that dependency chain.

Suggested versions are rstml 0.13.1 and rstml-control-flow 0.2.1.

Thank you!