Set the chart's placeholder version to 0.5.0

Cosmetic: make helm-package passes --version and --app-version from the
tag, so these two fields decide nothing about what gets published. Still
done, as with d502485 (0.4.0) and 88172ad (0.3.0) before it, because a
tree heading for v0.5.0 that still says 0.4.0 tells its reader
something false.

Co-authored-by: Claude <noreply@anthropic.com>

charts/terdut-operator/Chart.yaml

@@ -6,8 +6,8 @@ type: application
 # These fields decide nothing: `make helm-package` passes --version and
 # --app-version from the release tag (same reasoning as terdut-server's own
 # chart). They're for whoever reads the tree before a tag exists.
-version: 0.4.0
-appVersion: "v0.4.0"
+version: 0.5.0
+appVersion: "v0.5.0"
 
 keywords:
   - kubernetes