Use quotes for local project header includes

Replace angle brackets <...> with quotes "..." for project headers
to improve compatibility with IDEs and tooling.

While both forms are valid, many tools and IDEs treat quoted includes
as local files, enabling better indexing, navigation, and refactoring
support.

Author: mizdebsk

src/jurand.cpp

@@ -2,7 +2,7 @@
 #include <utility>
 #include <atomic>
 
-#include <java_symbols.hpp>
+#include "java_symbols.hpp"
 
 using namespace java_symbols;
 

src/jurand_test.cpp

@@ -1,7 +1,7 @@
 #include <iostream>
 #include <sstream>
 
-#include <java_symbols.hpp>
+#include "java_symbols.hpp"
 
 using namespace java_symbols;