chore(helm): update image docker.io/cthulhoo/ttrss-web-nginx digest to 78ab105 (#33100)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| docker.io/cthulhoo/ttrss-web-nginx | digest | `bbde2dd` -> `78ab105` |

Add the preset `:preserveSemverRanges` to your config if you don't want
to pin your dependencies.

---

### Configuration

📅 **Schedule**: Branch creation - At any time (no schedule defined),
Automerge - At any time (no schedule defined).

🚦 **Automerge**: Enabled.

♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the
rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about this update
again.

---

- [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check
this box

---

This PR has been generated by [Renovate
Bot](https://redirect.github.com/renovatebot/renovate).

<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiIzOS4xOTEuNCIsInVwZGF0ZWRJblZlciI6IjM5LjE5MS40IiwidGFyZ2V0QnJhbmNoIjoibWFzdGVyIiwibGFiZWxzIjpbImF1dG9tZXJnZSIsInJlbm92YXRlL2NvbnRhaW5lciIsInR5cGUvZGlnZXN0Il19-->

charts/stable/tt-rss/Chart.yaml

@@ -34,4 +34,4 @@ sources:
   - https://hub.docker.com/r/cthulhoo/ttrss-fpm-pgsql-static
   - https://hub.docker.com/r/cthulhoo/ttrss-web-nginx
 type: application
-version: 18.5.19
+version: 18.5.20

charts/stable/tt-rss/values.yaml

@@ -5,7 +5,7 @@ image:
 nginxImage:
   repository: docker.io/cthulhoo/ttrss-web-nginx
   pullPolicy: IfNotPresent
-  tag: latest@sha256:bbde2dd17c8f936d3983cb0f051ec4664b636c8b51bdb8454a79576dbef139de
+  tag: latest@sha256:78ab1052441c04d59588982f3b006bb9d513d29ab335d1ea5889fd039e131d66
 updaterImage:
   repository: docker.io/cthulhoo/ttrss-fpm-pgsql-static
   pullPolicy: IfNotPresent