Increased maintain to not miss closed at slow bauds

src/TinyGsmClientA6.h

@@ -217,7 +217,7 @@ public:
 
   void maintain() {
     //while (stream.available()) {
-      waitResponse(10, NULL, NULL);
+      waitResponse(50, NULL, NULL);
     //}
   }
 

src/TinyGsmClientESP8266.h

@@ -209,7 +209,7 @@ public:
   }
 
   void maintain() {
-      waitResponse(10, NULL, NULL);
+      waitResponse(50, NULL, NULL);
   }
 
   bool factoryDefault() {

src/TinyGsmClientM590.h

@@ -213,7 +213,7 @@ public:
 
   void maintain() {
     //while (stream.available()) {
-      waitResponse(10, NULL, NULL);
+      waitResponse(50, NULL, NULL);
     //}
   }
 

src/TinyGsmClientSIM800.h

@@ -253,7 +253,7 @@ public:
       }
     }
     while (stream.available()) {
-      waitResponse(10, NULL, NULL);
+      waitResponse(50, NULL, NULL);
     }
   }
 

src/TinyGsmClientU201.h

@@ -247,7 +247,7 @@ public:
       }
     }
     while (stream.available()) {
-      waitResponse(10, NULL, NULL);
+      waitResponse(50, NULL, NULL);
     }
   }