ci: set POSTGRES_HOST directly in workflow

.gitea/workflows/backend-tests.yaml

@@ -62,7 +62,7 @@ jobs:
         working-directory: backend
         run: go test -tags "test,dev" -count=1 -v -timeout 120s ./handlers/... ./auth/... ./mw/... ./internal/... ./db/...
         env:
-          TEST_DB_HOST: postgres
+          POSTGRES_HOST: postgres
           PGUSER: myuser
           PGPASSWORD: mypassword
           PGDATABASE: mydb

backend/db/db_test.go

@@ -13,7 +13,9 @@ import (
 
 func resetEnv() {
 	host := "localhost"
-	if h := os.Getenv("TEST_DB_HOST"); h != "" {
+	if h := os.Getenv("POSTGRES_HOST"); h != "" {
+		host = h
+	} else if h := os.Getenv("TEST_DB_HOST"); h != "" {
 		host = h
 	}
 	os.Setenv("POSTGRES_USER", "myuser")