Fix GCC 13 build error.

GCC removed the cstdint header from many other headers, so we can't rely on transitive includes to define these types. This led to a compile error in this file due to no more transitive inclusion.

pcb_calculator/eserie.h

@@ -18,6 +18,7 @@
  * with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <cstdint>
 #include <array>
 #include <vector>
 #include <string>