fix destination path for extension sql upgrade scripts

Author: eeeebbbbrrrr

cargo-pgx/src/commands/install.rs

@@ -158,8 +158,8 @@ fn copy_sql_files(extdir: &PathBuf, extname: &str, base_directory: &PathBuf) {
             let filename = sql.file_name().into_string().unwrap();
 
             if filename.starts_with(&format!("{}--", extname)) && filename.ends_with(".sql") {
-                let mut dest = PathBuf::new();
-                dest.push(&extdir);
+                let mut dest = base_directory.clone();
+                dest.push(extdir);
                 dest.push(filename);
 
                 copy_file(sql.path(), dest, "extension schema file");