fix: Fix incorrect interpreting strings with $ as env vars

[diogosilva30]

I noticed this bug where any string with a dollar sign $ is being treated as env var and then fails when trying to load such env var. Saw the problem is the regex is missing an anchor at start ˆ. Adding this will make sure value needs to start with $ and not randomly in middle of string.

Example of failure:

MY_PW: <L/f\U<Uj2{.S95@^$Rx

When trying to load with config parser:

Error reading configuration file: Environment variable <L/f\U<Uj2{.S95@^$Rx was not found

I've added unit tests to cover this scenario

diosil1@root python-config-parser % python test_configparser.py 
............
----------------------------------------------------------------------
Ran 12 tests in 0.002s

OK

@BrunoSilvaAndrade please review this?

[BrunoSilvaAndrade]

Hi @diogosilva30, sure thing, the pr is being reviewed and will be merged if everything is alright

[BrunoSilvaAndrade]

@joaosouzacoder can u review this?

[joaosouzacoder]

@diogosilva30 first of all, thank you for your contribution and for using our library.

I just reviewed the PR and I’m approving it.

[BrunoSilvaAndrade]

The v3.1.6 has been released

[diogosilva30]

Thank you both for fast review and all the work in put in for this library 👍