Fix bad environment.yml and test project

Author: Chuxel

containers/python-3-miniconda/environment.yml

@@ -1,3 +1,4 @@
-jupyter
-numpy
-matplotlib
+dependencies:
+  - jupyter
+  - numpy
+  - matplotlib

containers/python-3-miniconda/test-project/hello.py

@@ -19,7 +19,10 @@
        title='About as simple as it gets, folks')
 ax.grid()
 
-fig.savefig("plot.png")
+fig.savefig("test-project/plot.png")
 plt.show()
 
 print('Open test-project/plot.png to see the result!')
+
+
+#%%