fix: upgrade: add missing check for migration warnings and errors

Refs: https://codeberg.org/forgejo/forgejo/issues/6583

upgrade/upgrade.sh

@@ -57,6 +57,10 @@ function migration_assert() {
 
     grep --quiet 'ORM engine initialization successful' $logfile
     if grep 'serveInstalled() \[[EW]\] Table' $logfile; then
+        echo "unexpected warnings in database initialization"
+        return 1
+    fi
+    if grep 'Migrate() \[[EW]\]' $logfile; then
         echo "unexpected warnings in database migration"
         return 1
     fi
@@ -64,6 +68,8 @@ function migration_assert() {
 
 function test_gitea_upgrades() {
     local config=$UPGRADE_DIR/default-app.ini
+    # The Forgejo target migration version must be 10.0 because it is the last supported.
+    # https://forgejo.org/2024-12-gitea-compatibility/
     (
         echo gitea 1.21 forgejo 10.0
         echo gitea 1.22 forgejo 10.0