Incorrect parsing for interpolation within single quotes

[stone-w4tch3r]

Consider this code:

#.env
TEST_VAR='test'
TEST_VAR2='${TEST_VAR}'

Plugin does not highlight second variable's value as interpolated.

But docker compose correctly interpolates it, and TEST_VAR2 will have "test" value

[adelf]

Interpolated values aren't supported yet.