Fix indentation in templates

Use Jinja2 lstrip_blocks option in templates to ensure consistent
indentation in generated files.

roles/matrix-nginx-proxy/templates/nginx/conf.d/matrix-riot-web.conf.j2

@@ -1,3 +1,4 @@
+#jinja2: lstrip_blocks: "True"
 server {
 	listen {{ 8080 if matrix_nginx_proxy_enabled else 80 }};
 	server_name {{ matrix_nginx_proxy_proxy_riot_hostname }};