Package installation package from requirements does not work, "uses an insecure transport scheme"

Question

I am trying to install django-forms-builder through an entry in the requirements.txt file. At startup

pip install -r requirements.txt

I get an error

django-forms-builder/0.11.1 uses an insecure transport scheme (http). Consider using https if  has it available
django-forms-builder/ uses an insecure transport scheme (http). Consider using https if  has it available
Could not find any downloads that satisfy the requirement django-forms-builder==0.11.1 (from -r requirements.txt (line 33))

The message is very clear, it wants https, but I still need to install the package. It works when I install it separately outside the requirements file with a simple

pip install django-forms-builder

so how can i make demands accept it?