test: use `PYTHON` executable from env in `assertSnapshot`
One can pass a custom PYTHON
executable that is picked up by the Makefile
and some other tests
https://github.com/nodejs/node/blob/efe5b81df997780ac1ef7660c223e361dda2841e/Makefile#L312-L317 https://github.com/nodejs/node/blob/c0c7e866dc2bed108290a514fdd50db3c886c84f/test/parallel/test-child-process-set-blocking.js#L28
In assertSnapshot
, we rely on the hashbang line in pseudo-tty
:
https://github.com/nodejs/node/blob/9e5e2f1dc5cdd857d79f05981a53382e23a1d55b/tools/pseudo-tty.py#L1
For consistency, let's use the PYTHON
value when defined.