Dependencies fail to install when using `requirements.txt`

[asciidiego]

Although Docker is better than using this Buildpack for Conda, because I did not want to introduce more complexity to the micro-project I was developing, I needed to use pip.

The problem is that in

conda-buildpack/bin/steps/conda_compile

Line 22 in 87945f3

pip install -r requirements.txt --exists-action=w --allow-all-external | indent

the argument option called --allow-all-externals is deprecated in modern pip versions (>18.0).

So I deleted it, and the build worked in Heroku. Hope I could help somebody :)