fix: add pragma once to headers

src/client.hpp

@@ -1,3 +1,4 @@
+#pragma once
 #include <stdexcept>
 #include <sys/types.h>
 

src/csv.hpp

@@ -1,3 +1,4 @@
+#pragma once
 #include <fstream>
 #include <string>
 #include <vector>

src/data.hpp

@@ -1,3 +1,4 @@
+#pragma once
 #include <stdexcept>
 #include <sys/types.h>
 

src/mappings.hpp

@@ -1,3 +1,4 @@
+#pragma once
 #include <map>
 #include <optional>
 #include <string>

src/resourceloc.hpp

@@ -1,3 +1,4 @@
+#pragma once
 #include <string>
 namespace resourceloc {
 std::string resolve(std::string inp);

src/server.hpp

@@ -1,3 +1,4 @@
+#pragma once
 #include <stdexcept>
 #include <sys/types.h>