fix: Upgrade 헤더 유무에 따라 Connection 헤더의 값을 동적으로 설정하도록 (#581)

* fix: Upgrade 헤더 유무에 따라 Connection 헤더의 값을 동적으로 설정하도록

- Upgrade 헤더가 존재하면(e.g. WebSocket) upgrade로 설정
- Upgrade 헤더가 존재하지 않으면 keep-alive로 설정

* chore: 서브모듈 업데이트

Author: whqtker

docs/infra-config/nginx.dev.conf

@@ -1,3 +1,8 @@
+map $http_upgrade $connection_upgrade {
+    default upgrade;
+    ''      keep-alive;
+}
+
 server {
     listen 80;
     server_name api.stage.solid-connection.com;
@@ -40,6 +45,6 @@ server {
         proxy_set_header X-Forwarded-Proto $scheme;
         proxy_http_version 1.1;
         proxy_set_header Upgrade $http_upgrade;
-        proxy_set_header Connection "upgrade";
+        proxy_set_header Connection $connection_upgrade;
     }
 }

docs/infra-config/nginx.prod.conf

@@ -1,3 +1,8 @@
+map $http_upgrade $connection_upgrade {
+    default upgrade;
+    ''      keep-alive;
+}
+
 server {
     listen 80;
     server_name api.solid-connection.com;
@@ -31,6 +36,6 @@ server {
         proxy_set_header X-Forwarded-Proto $scheme;
         proxy_http_version 1.1;
         proxy_set_header Upgrade $http_upgrade;
-        proxy_set_header Connection "upgrade";
+        proxy_set_header Connection $connection_upgrade;
     }
 }