Add experimental support for pipenv

[yakky]

Add support to pipenv by enabling its usage as a pip replacement

Fix #341

[codecov]

Codecov Report

Merging #342 into develop will decrease coverage by 0.51%.
The diff coverage is 54.54%.

@@             Coverage Diff             @@
##           develop     #342      +/-   ##
===========================================
- Coverage     90.9%   90.39%   -0.52%     
===========================================
  Files            7        7              
  Lines          671      677       +6     
  Branches       142      144       +2     
===========================================
+ Hits           610      612       +2     
- Misses          28       30       +2     
- Partials        33       35       +2

Impacted Files	Coverage Δ
djangocms_installer/config/__init__.py	90.55% <100%> (+0.1%)	⬆️
djangocms_installer/install/__init__.py	79.24% <44.44%> (-6.47%)	⬇️

---

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[codecov]

Codecov Report

Merging #342 into develop will decrease coverage by 0.3%.
The diff coverage is 80.76%.

@@            Coverage Diff             @@
##           develop    #342      +/-   ##
==========================================
- Coverage     90.9%   90.6%   -0.31%     
==========================================
  Files            7       7              
  Lines          671     692      +21     
  Branches       142     148       +6     
==========================================
+ Hits           610     627      +17     
- Misses          28      29       +1     
- Partials        33      36       +3

Impacted Files	Coverage Δ
djangocms_installer/config/__init__.py	90.55% <100%> (+0.1%)	⬆️
djangocms_installer/install/__init__.py	83.82% <79.16%> (-1.9%)	⬇️

---

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Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 9fec66d...d949692. Read the comment docs.