Fix nginx location matching (mastodon#20198)

Author: keiya

dist/nginx.conf

@@ -58,7 +58,7 @@ server {
 
   # If Docker is used for deployment and Rails serves static files,
   # then needed must replace line `try_files $uri =404;` with `try_files $uri @proxy;`.
-  location = sw.js {
+  location = /sw.js {
     add_header Cache-Control "public, max-age=604800, must-revalidate";
     add_header Strict-Transport-Security "max-age=63072000; includeSubDomains";
     try_files $uri =404;