Cache Conda in CI (#74)

* Cache Conda in actions

* Cache hit check

* Make cache path a config

Author: pomadchin

.github/workflows/ci.yml

@@ -37,7 +37,25 @@ jobs:
           activate-environment: pdal-java
           channels: conda-forge
 
+      - name: Conda cache config
+        id: cache-config
+        run: | 
+          echo "today=$(/bin/date -u '+%Y%m%d')" >> $GITHUB_OUTPUT
+          echo "path=$CONDA/envs/pdal-java" >> $GITHUB_OUTPUT
+        shell: bash
+
+      - name: Cache Conda env
+        uses: actions/cache@v3
+        with:
+          path: ${{ steps.cache-config.outputs.path }}
+          key:
+            conda-pdal-java-${{ runner.os }}--${{ runner.arch }}--${{ steps.cache-config.outputs.today }}-${{ matrix.pdal }}-${{ env.CACHE_NUMBER }}
+        env:
+          CACHE_NUMBER: 0
+        id: conda-cache
+
       - name: Install PDAL
+        if: steps.conda-cache.outputs.cache-hit != 'true'
         run: conda install pdal=${{ matrix.pdal }}
 
       - name: Set LD_LIBRARY_PATH 
@@ -87,7 +105,25 @@ jobs:
           activate-environment: pdal-java
           channels: conda-forge
 
+      - name: Conda cache config
+        id: cache-config
+        run: | 
+          echo "today=$(/bin/date -u '+%Y%m%d')" >> $GITHUB_OUTPUT
+          echo "path=$CONDA/envs/pdal-java" >> $GITHUB_OUTPUT
+        shell: bash
+
+      - name: Cache Conda env
+        uses: actions/cache@v3
+        with:
+          path: ${{ steps.cache-config.outputs.path }}
+          key:
+            conda-pdal-java-${{ runner.os }}--${{ runner.arch }}--${{ steps.cache-config.outputs.today }}-${{ matrix.pdal }}-${{ env.CACHE_NUMBER }}
+        env:
+          CACHE_NUMBER: 0
+        id: conda-cache
+
       - name: Install PDAL
+        if: steps.conda-cache.outputs.cache-hit != 'true'
         run: conda install pdal=${{ matrix.pdal }}
 
       - name: Set LD_LIBRARY_PATH