Fix path joining

Author: mdboom

pyperformance/_pyproject_toml.py

@@ -85,7 +85,7 @@ def load_pyproject_toml(filename, *, name=None, tools=None, requirefiles=True):
     with open(filename, encoding="utf-8") as infile:
         text = infile.read()
 
-    symlink = os.path.join(filename, text.strip())
+    symlink = os.path.join(os.path.dirname(filename), text.strip())
     print(filename, symlink)
     if os.path.isfile(symlink):
         print('following')