TST Set minimal samtools version

Otherwise, conda will default to a very old version, which causes
issues.

.github/workflows/semibin_test.yml

@@ -29,7 +29,7 @@ jobs:
     - name: Install dependencies
       shell: bash -l {0}
       run : |
-        conda install -c conda-forge -c bioconda numpy pandas pytest hypothesis"<=6.112.1" python-igraph scikit-learn requests numexpr tqdm pytorch bedtools hmmer fraggenescan prodigal samtools mmseqs2
+        conda install -c conda-forge -c bioconda numpy pandas pytest hypothesis"<=6.112.1" python-igraph scikit-learn requests numexpr tqdm pytorch bedtools hmmer fraggenescan prodigal "samtools>=1.21" mmseqs2
         pip install .
     - name: Test with pytest
       shell: bash -l {0}