fix: exclude "async" example from static builds

The example starts a multi-threaded tokio runtime in the master process.

Author: bavshin-f5

.github/workflows/nginx.yaml

@@ -30,7 +30,7 @@ jobs:
       fail-fast: false
       matrix:
         module:
-          # static
+          - static
           - dynamic
         nginx-ref:
           # master

examples/config

@@ -4,7 +4,7 @@ ngx_cargo_profile=ngx-module
 if [ $HTTP = YES ]; then
     ngx_module_type=HTTP
 
-    if :; then
+    if [ "$ngx_module_link" = DYNAMIC ]; then
         ngx_module_name=ngx_http_async_module
         ngx_module_lib=async