Bump bwa mem version

[SPPearce]

The bwa mem +samtools docker container is currently failing with:

Command error:
  Unable to find image 'quay.io/biocontainers/bwa:0.7.17--hed695b0_7' locally
  0.7.17--hed695b0_7: Pulling from biocontainers/bwa
  docker: [DEPRECATION NOTICE] Docker Image Format v1 and Docker Image manifest version 2, schema 1 support is disabled by default and will be removed in an upcoming release. Suggest the author of quay.io/biocontainers/bwa:0.7.17--hed695b0_7 to upgrade the image to the OCI Format or Docker Image manifest v2, schema 2. More information at https://docs.docker.com/go/deprecated-image-specs/.
  See 'docker run --help'.

This PR updates bwa mem and samtools to the most recent versions, using this multicontainer. Note that other tools using bwa haven't been updated, if they exist; these can wait until the wave support comes in.