ci: allow us to skip builds with "no-ci-builds" label

.github/workflows/copr-builds.yml

@@ -15,6 +15,7 @@ permissions:
 
 jobs:
   build:
+    if: !contains(github.event.issue.labels.*.name, 'no-ci-builds')
     runs-on: ubuntu-latest
     name: RPM package
     strategy:

.github/workflows/fedora-tox.yml

@@ -6,6 +6,7 @@ on:
 name: Run Tox tests
 jobs:
   tox_test:
+    if: !contains(github.event.issue.labels.*.name, 'no-ci-builds')
     name: Tox test
     steps:
       - uses: actions/checkout@v3

.packit.yaml

@@ -2,6 +2,11 @@
 # https://packit.dev/docs/configuration/
 
 ---
+require:
+  label:
+    absent:
+      - no-ci-builds
+
 actions:
   create-archive:
     - bash -c "tito build --tgz --test -o ."