chore: add workflow-dispatch event into ui9-build GH action (#221)

Signed-off-by: Valeriy Svydenko <[email protected]>

Author: svor

.github/workflows/ubi9-build.yaml

@@ -4,6 +4,7 @@ name: Build of UBI 9 based Developer Images
 on:
   push:
     branches: [ main ]
+  workflow_dispatch:
 
   workflow_call:
     # Map the workflow outputs to job outputs