Try using libmamba solver for conda packaging

It is [officially supported by conda](https://www.anaconda.com/blog/conda-is-fast-now),
and it is significantly faster.

Before this commit, Windows packaging usually takes 1 hour and 15 minutes. Mac packaging
usually takes about 45 minutes. Linux usually takes about 35 minutes.

We'll see if there are any noticeable differences.

Signed-off-by: Patrick Avery <patrick.avery@kitware.com>

.github/workflows/container_build.sh

@@ -21,9 +21,12 @@ ${HOME}/miniconda3/bin/conda create --override-channels -c conda-forge -y -n hex
 ${HOME}/miniconda3/bin/activate hexrd
 ${HOME}/miniconda3/bin/conda activate hexrd
 
+# Install the libmamba solver (it is much faster)
+${HOME}/miniconda3/bin/conda install -n base -c conda-forge conda-libmamba-solver
+
 # Install conda build and create output directory
-${HOME}/miniconda3/bin/conda install --override-channels -c conda-forge conda-build -y
+${HOME}/miniconda3/bin/conda install --solver libmamba --override-channels -c conda-forge conda-build -y
 mkdir output
 
 # Build the package
-${HOME}/miniconda3/bin/conda build --override-channels -c conda-forge --output-folder output/ conda.recipe/
+${HOME}/miniconda3/bin/conda build --solver libmamba --override-channels -c conda-forge --output-folder output/ conda.recipe/

.github/workflows/package.yml

@@ -46,9 +46,11 @@ jobs:
     - name: Install build requirements
       run: |
           conda activate hexrd
+          # Change default solver to be libmamba, so that it runs much faster
+          conda install -n base -c conda-forge conda-libmamba-solver
           # FIXME: downgrade urllib3 until this issue is fixed:
           # https://github.com/Anaconda-Platform/anaconda-client/issues/654
-          conda install --override-channels -c conda-forge anaconda-client conda-build conda 'urllib3<2.0.0'
+          conda install --solver libmamba --override-channels -c conda-forge anaconda-client conda-build conda 'urllib3<2.0.0'
 
       # This is need to ensure ~/.profile or ~/.bashrc are used so the activate
       # command works.
@@ -59,7 +61,7 @@ jobs:
       run: |
           conda activate hexrd
           mkdir output
-          conda build --override-channels -c conda-forge --output-folder output/ conda.recipe/
+          conda build --solver libmamba --override-channels -c conda-forge --output-folder output/ conda.recipe/
       # This is need to ensure ~/.profile or ~/.bashrc are used so the activate
       # command works.
       shell: bash -l {0}