Track @v0 in the fa and zh-cn sync workflows (#584)

Completes the pin migration this repo started for French in #581.
Translation happens in the source repo's sync workflow, so these two
pins govern what engine version actually translates fa and zh-cn
content — and they were still on `@v0.16.1`, two releases behind.

Floating `@v0` is the policy settled in
QuantEcon/project-translation#9: it is the action's own documented
convention, its floating tags are well maintained, and development
tempo is fast enough that hand-bumping reliably lags the releases worth
having. The residual 0.x-may-break risk is mitigated not by the pin but
by sync output landing as a PR a human reviews before merge.

With these two, all nine translation workflow pins across the
programming trio track `@v0`, so future releases reach production on
merge rather than needing a rollout PR each time.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: mmcky

.github/workflows/sync-translations-fa.yml

@@ -24,7 +24,7 @@ jobs:
         with:
           fetch-depth: 2
 
-      - uses: QuantEcon/action-translation@v0.16.1
+      - uses: QuantEcon/action-translation@v0
         with:
           mode: sync
           target-repo: QuantEcon/lecture-python-programming.fa

.github/workflows/sync-translations-zh-cn.yml

@@ -24,7 +24,7 @@ jobs:
         with:
           fetch-depth: 2
 
-      - uses: QuantEcon/action-translation@v0.16.1
+      - uses: QuantEcon/action-translation@v0
         with:
           mode: sync
           target-repo: QuantEcon/lecture-python-programming.zh-cn