Support sketch paths outside of workspace

Some code that is used to provide user-friendly paths relative to the root of the repository, rather than unfamiliar absolute paths that expose the full folder structure of the docker container in log messages was written under the assumption that the paths provided by the user to the sketch-paths input will always be within the repository (GITHUB_WORKSPACE). The user may wish to compile example sketches of installed libraries, which are located outside GITHUB_WORKSPACE. Previously, this would result in a workflow failure:

ValueError: '/github/home/Arduino/libraries/FooLibrary/examples/Bar' does not start with '/github/workspace'

Author: per1234

compilesketches/compilesketches.py

@@ -1047,8 +1047,14 @@ def path_relative_to_workspace(path):
     Keyword arguments:
     path -- the path to make relative
     """
-    path = pathlib.PurePath(path)
-    return path.relative_to(os.environ["GITHUB_WORKSPACE"])
+    path = pathlib.Path(path)
+    try:
+        relative_path = path.relative_to(os.environ["GITHUB_WORKSPACE"])
+    except ValueError:
+        # Path is outside workspace, so just use the given path
+        relative_path = path
+
+    return relative_path
 
 
 def absolute_path(path):

compilesketches/tests/test_compilesketches.py

@@ -1506,6 +1506,8 @@ def test_path_relative_to_workspace(monkeypatch):
     assert compilesketches.path_relative_to_workspace(path=pathlib.PurePath("/fooWorkspace", "baz")
                                                       ) == pathlib.PurePath("baz")
     assert compilesketches.path_relative_to_workspace(path="/fooWorkspace/baz") == pathlib.PurePath("baz")
+    # Test path outside workspace
+    assert compilesketches.path_relative_to_workspace(path="/bar/foo") == pathlib.PurePath("/bar/foo")
 
 
 @pytest.mark.parametrize("path, expected_absolute_path", [("/asdf", "/asdf"), ("asdf", "/fooWorkspace/asdf")])