Install poetry dependencies with --no-root (go-gitea#27919)

Poetry 1.7.0 or higher will print a warning otherwise, see discussions:

python-poetry/poetry#8369
python-poetry/poetry#1132

> --no-root Do not install the root package (the current project).

Author: silverwind

Makefile

@@ -922,7 +922,7 @@ node_modules: package-lock.json
 	@touch node_modules
 
 .venv: poetry.lock
-	poetry install
+	poetry install --no-root
 	@touch .venv
 
 .PHONY: update