Upgraded to xtensor 0.21.4

Author: JohanMabille

.appveyor.yml

@@ -22,7 +22,7 @@ install:
   - conda update -q conda
   - conda info -a
   - conda install gtest cmake -c conda-forge
-  - conda install xtensor=0.20.5 -c conda-forge
+  - conda install xtensor=0.21.4 -c conda-forge
   - cmake -G "NMake Makefiles" -D CMAKE_INSTALL_PREFIX=%MINICONDA%\\LIBRARY -DBUILD_TESTS=ON .
   - nmake test_xframe
   - cd test

.travis.yml

@@ -101,7 +101,7 @@ install:
     - conda install setuptools
     - conda update -q conda
     - conda install cmake -c conda-forge
-    - conda install xtensor=0.20.5 -c conda-forge
+    - conda install xtensor=0.21.4 -c conda-forge
     # Testing
     - mkdir build
     - cd build

README.md

@@ -18,7 +18,7 @@
 
 |  xframe  |  xtensor  |
 |----------|-----------|
-|  master  |  ^0.20.0  |
+|  master  |  ^0.21.4  |
 |   0.2.0  |  ^0.20.0  |
 |   0.1.0  |  ^0.19.1  |
 |   0.0.2  |  ^0.19.1  |