update action to dagger 0.2

- Remove AGE key setup
- Update README to use `dagger do`
- Update tests to dagger 0.2

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>

test/cue.mod/pkg/universe.dagger.io/python/python.cue

@@ -0,0 +1,29 @@
+// Helpers to run python programs
+package python
+
+import (
+	"universe.dagger.io/docker"
+
+	"universe.dagger.io/alpine"
+)
+
+// Run a python script in a container
+#Run: {
+	// Contents of the python script
+	script: string
+
+	// FIXME: don't pass the script as argument: write to filesystme instead
+	docker.#Run & {
+		command: {
+			name: "python"
+			flags: "-c": script
+		}
+
+		// As a convenience, image defaults to a ready-to-use python environment
+		image: docker.#Image | *_defaultImage
+
+		_defaultImage: alpine.#Image & {
+			packages: python: version: "3"
+		}
+	}
+}