get config file location from cli

src/main.zig

@@ -85,7 +85,16 @@ pub fn main() !void {
 
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
     const allocator = gpa.allocator();
-    const config = try readConfig(allocator, "config.json");
+
+    var args = std.process.args();
+    _ = args.skip();
+
+    const config_path = args.next();
+
+    const config = blk: {
+        break :blk if (config_path) |path| try readConfig(allocator, path) else try readConfig(allocator, "config.json");
+    };
+
     defer config.deinit();
 
     const b64 = std.base64.standard.Encoder;