Fixing composer install inside docker app container

[ammardev]

Describe the bug
Can not run composer install inside app docker container. The error appears because Composer can not find git.

Steps To Reproduce
Steps to reproduce the behavior:
The same steps explained in the README file.

1. Clone master branch.
2. Run the command: docker-compose run app composer install.
3. The error appears as the image in screenshots.

Expected behavior
Installing Packages inside Docker container.

Screenshots
Tested on my local machine and on a Digitalocean droplet.

My Configuration:

• Exact BookStack Version: The version of master branch.
• PHP Version: 7.3
• Hosting Method (Nginx/Apache/Docker): Docker.

This pull request adding git to the docker image. So Composer can install packages without the git error.

[ssddanbrown]

Thanks for reporting and fixing @3mmarg97.