envFile underscore variables don't make it to os.environ

[Murtagy]

Environment data

• debugpy version: 1.6.0
• OS and version: OSX 12.3.1
• Python version (& distribution if applicable, e.g. Anaconda): 3.10
• Using VS Code or Visual Studio: VS Code 1.67.1

Actual behavior

variable in env file:
_TEST=test

os.environ['_TEST'] is not present

Expected behavior

variable in env file:
_TEST=test

os.environ['_TEST'] == 'test'

Steps to reproduce:

1. Create env file with _TEST=test
2. Set envFile to absolute path of 1)
3. Run debugger and inspect in runtime import os; os.environ

[int19h]

@karthiknadig I believe it is due to this regex requiring the first character of variable name to be a letter:

vscode-python/src/client/common/variables/environment.ts

Line 105 in 3698950

const match = line.match(/^\s*([a-zA-Z]\w*)\s*=\s*(.*?)?\s*$/);

[Murtagy]

Perhaps changing to
const match = line.match(/^\s*(_?)([a-zA-Z]\w*)\s*=\s*(.*?)?\s*$/);
might be a solution