Small RAM savings in WebServer

From espressif/arduino-esp32#9594

Author: earlephilhower

Diff for: libraries/WebServer/src/Parsing.cpp

@@ -37,7 +37,7 @@
 
 #define __STR(a) #a
 #define _STR(a) __STR(a)
-const char * _http_method_str[] = {
+static const char * _http_method_str[] = {
 #define XX(num, name, string) _STR(name),
     HTTP_METHOD_MAP(XX)
 #undef XX