fix(gts): minor updates to GoToSocial

- Do not allow custom CSS anymore.
- Upgrade the base Alpine docker image to v3.20.
- Restyle the bullet points in the Night Owl CSS theme.

assets/gotosocial/themes/night-owl.css

@@ -125,3 +125,10 @@ a:hover, a:active {
   color: var(--night-owl-button-dark);
   transition: 0.5s
 }
+
+ul {
+  li::before {
+     color: var(--night-owl-light-purple);
+     content: "\29BF";
+  }
+}

config

@@ -1 +1 @@
-Subproject commit 68ec757f985e0626603bd5e47ecfdcb2e49de2d9
+Subproject commit fb6c324a1af6b9f21173be9e575e1a881d6f24b1

templates/gotosocial/Dockerfile.gotmpl

@@ -1,5 +1,5 @@
 # syntax=docker/dockerfile:1
-FROM alpine:3.19
+FROM alpine:3.20
 
 WORKDIR /tmp