change: make converted referenced pytest files always relative to project RootDir

tests/data/a-b.c/2 3.yml

@@ -6,7 +6,7 @@ config:
 teststeps:
 -
     name: request with functions
-    testcase: 1.yml
+    testcase: a-b.c/1.yml
     export:
         - session_foo2
 -

tests/data/a-b.c/debugtalk.py

@@ -1,13 +0,0 @@
-from httprunner import __version__
-
-
-def get_httprunner_version():
-    return __version__
-
-
-def sum_two(m, n):
-    return m + n
-
-
-def get_variables():
-    return {"foo1": "session_bar1"}