Update miniconda to 4.7.12.1 (#113)

Update miniconda to 4.7.12.1

Author: humitos

Dockerfile

@@ -14,7 +14,7 @@ ENV PYTHON_VERSION_36 3.6.8
 ENV PYTHON_VERSION_37 3.7.3
 ENV PYTHON_VERSION_38 3.8.0
 ENV PYPY_VERSION_35 pypy3.5-7.0.0
-ENV CONDA_VERSION 4.6.14
+ENV CONDA_VERSION 4.7.12.1
 LABEL python.version_27=$PYTHON_VERSION_27
 LABEL python.version_35=$PYTHON_VERSION_35
 LABEL python.version_36=$PYTHON_VERSION_36