Set the chart's placeholder version to 0.7.1

Cosmetic: make helm-package passes --version and --app-version from the
tag, so these fields decide nothing about what is published. They are kept
in step so the tree heading for v0.7.1 does not say 0.7.0, as in
the 0.7.0 placeholder commit and 295dc3a.

Claude-Session: https://claude.ai/code/session_016mBLURvJoMuUEr9cB2RpUN

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: 0.7.0
-appVersion: "v0.7.0"
+version: 0.7.1
+appVersion: "v0.7.1"
 
 keywords:
   - kubernetes