fix(Jira): Handling of issues with no priority label (#573)

The code seems to work! ...In the case where there is a priority label
on the issue. Jira complains if the priority field is just "", so we
need to get rid of it

.github/workflows/issue.yml

@@ -45,21 +45,23 @@ jobs:
       if: ${{ contains(github.event.issue.labels.*.name, 'bug') }}
       env:
         JIRA_PRIORITY: ${{ steps.set_priority_var.outputs.JIRA_PRIORITY }}
+        JIRA_PRIORITY_FIELD: ', "priority": { "name": "${{ env.JIRA_PRIORITY }}" }'
       with:
         project: TKET
         issuetype: Bug
         summary: « [hugr] ${{ github.event.issue.title }}»
         description: ${{ github.event.issue.html_url }}
-        fields: '{"labels": ["hugr"], "priority": { "name": "${{ env.JIRA_PRIORITY }}" }}'
+        fields: '{ "labels": ["hugr"] ${{ env.JIRA_PRIORITY_FIELD }} }'
 
     - name: Create Task
       uses: atlassian/gajira-create@v3.0.1
       if: ${{ ! contains(github.event.issue.labels.*.name, 'bug') }}
       env:
         JIRA_PRIORITY: ${{ steps.set_priority_var.outputs.JIRA_PRIORITY }}
+        JIRA_PRIORITY_FIELD: ', "priority": { "name": "${{ env.JIRA_PRIORITY }}" }'
       with:
         project: TKET
         issuetype: Task
         summary: « [hugr] ${{ github.event.issue.title }}»
         description: ${{ github.event.issue.html_url }}
-        fields: '{"labels": ["hugr"], "priority": { "name": "${{ env.JIRA_PRIORITY }}" }}'
+        fields: '{ "labels": ["hugr"] ${{ env.JIRA_PRIORITY_FIELD }} }'