Enable github action concurency

[twisted-trac]

	@adiroiban reported
Trac ID	trac#10246
Type	enhancement
Created	2021-08-01 15:33:53Z

concurrency: 
  group: ${{ github.head_ref }}
  cancel-in-progress: ${{ github.head_ref != 'refs/heads/trunk' }}

Searchable metadata

trac-id__10246 10246
type__enhancement enhancement
reporter__adiroiban adiroiban
priority__normal normal
milestone__None None
branch__ 
branch_author__ 
status__closed closed
resolution__fixed fixed
component__core core
keywords__review review
time__1627832033030901 1627832033030901
changetime__1628695753944213 1628695753944213
version__None None
owner__Adi_Roiban__adiroiban_____ Adi Roiban <adiroiban@...>

[twisted-trac]

	@adiroiban commented

pr at #1648

[twisted-trac]

	@adiroiban set owner to @adiroiban @adiroiban set status to closed

In changeset fcd8f3c

#!CommitTicketReference repository="" revision="fcd8f3cac8c349cfee3f3068e45d8b4f810394b7"
Merge pull request #1648 from twisted/10246-gha-concurency

Merge pull request #123 from twisted/4356-branch-name-with-trac-id

Author: adiroiban
Reviewer: altendky 
Fixes: ticket:10246

Enable GitHub Actions concurrency for the test workflow.