Do not run Conda test GHA on MacOS ARM64

Do not run the Conda environment test on MacOS ARM64, as the `subread`
package is not available there.

.github/workflows/setup.yml

@@ -20,8 +20,10 @@ jobs:
         env: [snakemake, nextflow, jupyter, quarto]
         include:
           - env: snakemake
+            os: ubuntu-latest # Conda on MacOS ARM64 doesn't have subread
             cmd: snakemake -c 1 -d tutorials/snakemake/ -s tutorials/snakemake/snakefile_mrsa.smk
           - env: nextflow
+            os: ubuntu-latest # Conda on MacOS ARM64 doesn't have subread
             cmd: cd tutorials/nextflow && nextflow run main_mrsa.nf
           - env: jupyter
             cmd: jupyter nbconvert --to HTML tutorials/jupyter/supplementary_material.ipynb