try free-disk-space Action and unpin snakemake for linting, as well

.github/workflows/main.yml

@@ -29,7 +29,7 @@ jobs:
     steps:
     - uses: actions/checkout@v2
     - name: Lint workflow
-      uses: snakemake/snakemake-github-action@v1.25.1
+      uses: snakemake/snakemake-github-action@v1
       with:
         directory: .
         snakefile: workflow/Snakefile
@@ -42,6 +42,22 @@ jobs:
       - Linting
       - Formatting
     steps:
+    - name: Free Disk Space (Ubuntu)
+      uses: jlumbroso/[email protected]
+      with:
+        # this might remove tools that are actually needed,
+        # if set to "true" but frees about 6 GB
+        tool-cache: false
+
+        # all of these default to true, but feel free to set to
+        # "false" if necessary for your workflow
+        android: true
+        dotnet: true
+        haskell: true
+        large-packages: true
+        docker-images: true
+        swap-storage: true
+
     - uses: actions/checkout@v2
 
     - name: Test workflow (local FASTQs)