konflux: add all supported build platforms

Signed-off-by: Andrew Schoen <aschoen@ibm.com>

Author: andrewschoen

.tekton/snmp-notifier-6-1-pull-request.yaml

@@ -30,6 +30,8 @@ spec:
   - name: build-platforms
     value:
     - linux/x86_64
+    - linux/s390x
+    - linux/ppc64le
   - name: dockerfile
     value: Dockerfile
   - name: path-context

.tekton/snmp-notifier-6-1-push.yaml

@@ -27,6 +27,8 @@ spec:
   - name: build-platforms
     value:
     - linux/x86_64
+    - linux/s390x
+    - linux/ppc64le
   - name: dockerfile
     value: Dockerfile
   - name: path-context