Correctly deallocate external typed data

[vlad9486]

This works well.

Closes #61

[shekohex]

Looks like Valgrind did not pass this new change.

[vlad9486]

I tried running the same CI action on the master branch and vargrind fails there too. It is not my commit.

[shekohex]

I did run in a codespace, on github, on master branch: no issue

[vlad9486]

Please, try run CI again

[shekohex]

It looks like this issue happens when using rust nightly, on rust stable it works fine. The CI is using nightly rust for testing, for some reason.

Let me change the CI to work with stable rust instead.