Revert "Add pygtrie dependency for CI"

This reverts commit a943c9758eab267abe736a130d0ee10b3a1eefd4.

Author: dbarbier

.appveyor.yml

@@ -16,7 +16,6 @@ install:
   - conda create -q -n test-environment python=%PYTHON_VERSION% numpy scipy scikit-learn pandas joblib pytest
   - activate test-environment
   - conda install -c conda-forge dlib=19.17
-  - pip install pygtrie
   - pip install imageio
   - pip install scikit-image
 

ci/.travis_install.sh

@@ -40,7 +40,6 @@ fi
 conda install matplotlib
 conda install jupyter
 conda install pytest
-pip install pygtrie
 
 
 if [ "${IMAGE}" = "true" ]; then

requirements.txt

@@ -2,6 +2,5 @@ scipy>=1.2.1
 numpy>=1.16.2
 pandas>=0.24.2
 scikit-learn>=0.20.3
-pygtrie>=1.0
 matplotlib>=3.0.0
 joblib>=0.13.2