Remove secret key from .env.example

[hirenchalodiya1]

Issue

• Remove a secret key from the .env.example file as it may affect security.

Expected

• The secret key should not be public.

  Actual

• The environment file contains a secret key.

Changes

• Remove the secret key from the environment file.
• Add a secret key in the Travis environment.
• Add a secret key in the GitHub workflow environment.

[anshulahuja98]

That's a dummy key It's alright