release: only run one release action at a time (#231)

.github/workflows/release-branches.yml

@@ -9,6 +9,7 @@ on:
 
 jobs:
   release:
+    concurrency: release
     runs-on: ubuntu-latest
     permissions:
       id-token: write # In order to request a JWT for AWS auth

.github/workflows/release-prs.yml

@@ -10,6 +10,7 @@ on:
 
 jobs:
   release:
+    concurrency: release
     # Only intra-repo PRs are allowed to have PR artifacts uploaded
     if: github.event.pull_request.head.repo.full_name == 'DeterminateSystems/nix-installer' && contains(github.event.pull_request.labels.*.name, 'upload to s3')
     runs-on: ubuntu-latest

.github/workflows/release-tags.yml

@@ -7,6 +7,7 @@ on:
 
 jobs:
   release:
+    concurrency: release
     runs-on: ubuntu-latest
     permissions:
       contents: write # In order to upload artifacts to GitHub releases