feat(CLOUDDST-22843): Added signtractions python package

Signtractions is wrapper for pubtools-sign project which
allows signing containers with cosign.
This commit is related to the
konflux-ci/release-service-catalog#442
which use project signtractions as tekton task for signing
containers in release snapshots

Signed-off-by: Jindrich Luza <[email protected]>

Dockerfile

@@ -28,7 +28,8 @@ RUN dnf -y --setopt=tsflags=nodocs install \
 
 RUN pip3 install jinja2 \
     jinja2-ansible-filters \
-    packageurl-python
+    packageurl-python \
+    signtractions
 
 ADD data/certs/2015-IT-Root-CA.pem data/certs/2022-IT-Root-CA.pem /etc/pki/ca-trust/source/anchors/
 RUN update-ca-trust