Do less git magic

```julia
julia script.jl .. interactjl-test3
Reinitialized existing Git repository in /home/shashi/code/testapp/.git/
› Warning: heroku update available from 7.39.0 to 7.39.1.
Creating ⬢ interactjl-test3... done
Setting buildpack to https://github.com/Optomatica/heroku-buildpack-julia.git... done
https://interactjl-test3.herokuapp.com/ | https://git.heroku.com/interactjl-test3.git
On branch master
nothing to commit, working tree clean
ERROR: LoadError: failed process: Process(`git commit -m 'Initial commit'`, ProcessExited(1)) [1]
Stacktrace:
[1] run at ./process.jl:438 [inlined]
[2] main() at /home/shashi/code/testapp/interact-deploy/script.jl:74
[3] top-level scope at /home/shashi/code/testapp/interact-deploy/script.jl:78
in expression starting at /home/shashi/code/testapp/interact-deploy/script.jl:78
```

If an app repo is not a git repository, we shouldn't try to create one. We should just say not a git repository, please make it one.