Added environment.yml and requirements.txt to work with GitHub actions.

Author: rbanerjee20

environment.yml

@@ -1,9 +1,8 @@
-name: waves-fdm
+name: devito-book
 channels:
+  - defaults
   - conda
 dependencies:
-  - matplotlib
-  - numpy
   - pip
   - pip:
-    - devito
+    - -r file:requirements.txt

requirements.txt

@@ -0,0 +1,20 @@
+pip>=9.0.1
+numpy>=1.14
+sympy<1.6
+scipy
+pytest>=3.6
+pytest-runner
+flake8>=2.1.0
+nbval
+cached-property
+psutil>=5.1.0
+py-cpuinfo
+cgen>=2020.1
+codepy>=2019.1
+click
+codecov
+pytest-cov
+multidict
+anytree>=2.4.3
+pyrevolve>=2.1.3
+distributed<2.20