fix metadata issues with uppercase letters

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

util/ctx/ctx.go

@@ -3,7 +3,6 @@ package ctx
 import (
 	"context"
 	"net/http"
-	"net/textproto"
 	"strings"
 
 	"github.com/unistack-org/micro/v3/metadata"
@@ -13,10 +12,11 @@ func FromRequest(r *http.Request) context.Context {
 	ctx := r.Context()
 	md, ok := metadata.FromContext(ctx)
 	if !ok {
-		md = make(metadata.Metadata)
+		// create needed map with specific len
+		md = make(metadata.Metadata, len(r.Header)+2)
 	}
-	for k, v := range r.Header {
-		md[textproto.CanonicalMIMEHeaderKey(k)] = strings.Join(v, ",")
+	for key, val := range r.Header {
+		md.Set(key, strings.Join(val, ","))
 	}
 	// pass http host
 	md["Host"] = r.Host