Remove HEAD section of run name due to NF issue

nextflow doesn't like double dashes in run names for some reason. This would occur when there was a PR from a fork rather than a branch.

Author: jfy133

.github/workflows/ci.yml

@@ -32,7 +32,7 @@ jobs:
           docker pull nfcore/eager:dev && docker tag nfcore/eager:dev nfcore/eager:dev
       - name: Extract branch name
         shell: bash
-        run: echo "::set-env name=RUN_NAME::`echo ${GITHUB_REPOSITORY//\//_}`-`echo ${GITHUB_HEAD_REF//\//@} | rev | cut -f1 -d@ | rev`-${{ github.event_name }}-`echo ${GITHUB_SHA} | cut -c1-6`"
+        run: echo "::set-env name=RUN_NAME::`echo ${GITHUB_REPOSITORY//\//_}`-${{ github.event_name }}-`echo ${GITHUB_SHA} | cut -c1-6`"
         id: extract_branch
       - name: Determine tower usage
         shell: bash