Fix issue #137: fix wrongly recognize activating environment command error.

[BeiChenStanly]

Fix issue #137: Manim session could not be started. There was a problem running the manimgl command.

[BeiChenStanly]

@Splines Could you please review this pr? I believe it is an important fix.

[Splines]

@BeiChenStanly Sorry for the delay, I will look into it this Friday. Thanks for the PR.

In the meantime, could you please upgrade the PR description to include a short description of how your proposed solution fixes the problem? E.g. explain which commands are invoked that don't start with "manimgl" etc.

[BeiChenStanly]

@Splines Thank you for your review!
The error occurs when the terminal runs environment activating command automatically, which is called by some extension, and we wrongly recognize it as our manimgl command. It is fatal when the command finishes, that is, we will think that the manimgl command ends.

So we just care about the command started with manimgl.

screen.mp4

[Splines]

@BeiChenStanly Thanks, yeah this makes sense. And sorry, I was too ambitious in my timeplan saying that I will merge & release last Friday. Even though it's just a small change, but I might have to adapt the test pipeline and want to add some other notes to the Readme as well before the next release. So more realistically, this will be published in the first or second week of September. Thanks for your understanding.