style: format code with Go fmt and Gofumpt

This commit fixes the style issues introduced in ac63bfb according to the output
from Go fmt and Gofumpt.

Details: #1

Author: deepsource-autofix[bot]

lura/proxy.go

@@ -36,8 +36,8 @@ var (
 // Middleware creates a proxy that instruments the proxy it wraps by creating an span if enabled,
 // and report the duration of this stage in metrics if enabled.
 func Middleware(gsf state.GetterFn, metricsEnabled bool, tracesEnabled bool,
-	stageName string, urlPattern string, staticAttrs []attribute.KeyValue) proxy.Middleware {
-
+	stageName string, urlPattern string, staticAttrs []attribute.KeyValue,
+) proxy.Middleware {
 	if gsf == nil {
 		gsf = state.GlobalState
 	}