Update "requirements.txt" file.

requirements.txt

@@ -2,7 +2,7 @@ alabaster==0.7.12
 appnope==0.1.0
 aspy.yaml==1.3.0
 atomicwrites==1.3.0
-attrs==19.2.0
+attrs==19.3.0
 Babel==2.7.0
 backcall==0.1.0
 backports.functools-lru-cache==1.5
@@ -11,7 +11,6 @@ bleach==3.1.0
 certifi==2019.9.11
 cfgv==2.0.1
 chardet==3.0.4
-colour-demosaicing==0.1.4
 coverage==4.5.4
 coveralls==1.8.2
 cycler==0.10.0
@@ -27,7 +26,7 @@ imageio==2.6.1
 imagesize==1.1.0
 importlib-metadata==0.23
 invoke==1.3.0
-ipykernel==5.1.2
+ipykernel==5.1.3
 ipython==7.8.0
 ipython-genutils==0.2.0
 ipywidgets==7.5.1
@@ -37,7 +36,7 @@ jsonschema==3.1.1
 jupyter==1.0.0
 jupyter-client==5.3.4
 jupyter-console==6.0.0
-jupyter-core==4.6.0
+jupyter-core==4.6.1
 kiwisolver==1.1.0
 latexcodec==1.0.7
 MarkupSafe==1.1.1
@@ -48,19 +47,19 @@ mock==3.0.5
 more-itertools==7.2.0
 nbconvert==5.6.0
 nbformat==4.4.0
-networkx==2.3
+networkx==2.4
 nodeenv==1.3.3
 nose==1.3.7
 notebook==6.0.1
-numpy==1.17.2
+numpy==1.17.3
 oset==0.1.3
 packaging==19.2
 pandas==0.24.2
 pandocfilters==1.4.2
 parso==0.5.1
 pexpect==4.7.0
 pickleshare==0.7.5
-Pillow==6.2.0
+Pillow==6.2.1
 pkginfo==1.5.0.1
 pluggy==0.13.0
 pre-commit==1.18.3
@@ -107,7 +106,7 @@ tqdm==4.36.1
 traitlets==4.3.3
 twine==1.15.0
 urllib3==1.25.6
-virtualenv==16.7.5
+virtualenv==16.7.7
 wcwidth==0.1.7
 webencodings==0.5.1
 widgetsnbextension==3.5.1