Fix the Trim function to include all whitespace characters

Author: psx95

api/include/opentelemetry/common/string_util.h

@@ -15,11 +15,11 @@ class StringUtil
 public:
   static nostd::string_view Trim(nostd::string_view str, size_t left, size_t right) noexcept
   {
-    while (left <= right && str[static_cast<std::size_t>(left)] == ' ')
+    while (left <= right && isspace(str[left]))
     {
       left++;
     }
-    while (left <= right && str[static_cast<std::size_t>(right)] == ' ')
+    while (left <= right && isspace(str[right]))
     {
       right--;
     }