more permissive requirements.txt

Author: SebastianoF

requirements.txt

@@ -1,11 +1,11 @@
 matplotlib
-nibabel==2.3.3
-numpy==1.16.0
-pandas==0.23.4
-pytest==4.1.1
-scipy==1.2.0
-setuptools==40.6.3
-scikit-image==0.14.2
-sympy==1.3
-tabulate==0.8.2
-scikit_learn==0.20.2
+nibabel>=2.3.3
+numpy>=1.16.0
+pandas>=0.23.4
+pytest>=4.1.1
+scipy>=1.2.0
+setuptools>=40.6.3
+scikit-image>=0.14.2
+sympy>=1.3
+tabulate>=0.8.2
+scikit_learn>=0.20.2