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/dagger.io/dagger/http.cue

@@ -0,0 +1,47 @@
+package dagger
+
+// HTTP operations
+
+// Raw buildkit API
+//
+// package llb // import "github.com/moby/buildkit/client/llb"
+//
+// func HTTP(url string, opts ...HTTPOption) State
+//
+// type HTTPOption interface {
+//         SetHTTPOption(*HTTPInfo)
+// }
+// func Checksum(dgst digest.Digest) HTTPOption
+// func Chmod(perm os.FileMode) HTTPOption
+// func Chown(uid, gid int) HTTPOption
+// func Filename(name string) HTTPOption
+
+// Fetch a file over HTTP
+#HTTPFetch: {
+	$dagger: task: _name: "HTTPFetch"
+
+	// Source url
+	// Example: https://www.dagger.io/index.html
+	source: string
+
+	// Destination path of the downloaded file
+	// Example: "/downloads/index.html"
+	dest: string
+
+	// Optionally verify the file checksum
+	// FIXME: what is the best format to encode checksum?
+	checksum?: string
+
+	// Optionally set file permissions on the downloaded file
+	// FIXME: find a more developer-friendly way to input file permissions
+	permissions?: int
+
+	// Optionally set UID of the downloaded file
+	uid?: int
+
+	// Optionally set GID of the downloaded file
+	gid?: int
+
+	// New filesystem state containing the downloaded file
+	output: #FS
+}