fix(migration): atomic /usr/bin/update replacement to prevent syntax errors

All 8 migration scripts (runtipi, dockge, dokploy, coolify, komodo,
alpine-komodo, overseerr, jellyseerr) overwrote /usr/bin/update in-place
while the parent shell still had the file open for reading. Since the
new content is longer than the original, bash would read leftover bytes
after the child process exited, causing garbled output or syntax errors
like: /usr/bin/update: line 2: syntax error near unexpected token )

Fix:
- Write to a temp file first, then mv over /usr/bin/update (atomic
  inode replacement so parent shell sees EOF on old fd)
- Remove unnecessary shebang from heredoc content in overseerr/jellyseerr
  (consistent with all other update scripts and install.func)

CHANGELOG.md

@@ -416,7 +416,6 @@ Exercise vigilance regarding copycat or coat-tailing sites that seek to exploit
 
   - #### 🐞 Bug Fixes
 
-    - addon migrations: /usr/bin/update replacement to prevent syntax error [@MickLesk](https://github.com/MickLesk) ([#12540](https://github.com/community-scripts/ProxmoxVE/pull/12540))
     - fix(immich): correct LibRaw clone URL to official upstream [@DenislavDenev](https://github.com/DenislavDenev) ([#12526](https://github.com/community-scripts/ProxmoxVE/pull/12526))
 
 ### 💾 Core

misc/tools.func

@@ -6500,13 +6500,14 @@ function setup_postgresql() {
   local SUITE
   case "$DISTRO_CODENAME" in
   trixie | forky | sid)
+
     if verify_repo_available "https://apt.postgresql.org/pub/repos/apt" "trixie-pgdg"; then
       SUITE="trixie-pgdg"
+
     else
-      msg_warn "PGDG repo not available for ${DISTRO_CODENAME}, falling back to distro packages"
-      USE_PGDG_REPO=false setup_postgresql
-      return $?
+      SUITE="bookworm-pgdg"
     fi
+
     ;;
   *)
     SUITE=$(get_fallback_suite "$DISTRO_ID" "$DISTRO_CODENAME" "https://apt.postgresql.org/pub/repos/apt")