Add compilers to conda environment

This fixes issues with `libstdc++.so` when using a system with a newer
compiler. In such cases, the compiler will create links to new symbols,
but the shared library available at runtime from conda-forge will not
have them available.

environment.yml

@@ -11,6 +11,8 @@ channels:
 dependencies:
   # runtime dependencies
   - cairocffi
+  - c-compiler
+  - cxx-compiler
   - contourpy>=1.0.1
   - cycler>=0.10.0
   - fonttools>=4.22.0
@@ -21,6 +23,7 @@ dependencies:
   - numpy>=1.23
   - pillow>=8
   - pkg-config
+  - python
   - pygobject
   - pyparsing>=2.3.1
   - pyqt