Mark version number as develoment

Co-authored-by: Christian Meusel <christian.meusel@posteo.de>

Author: eldruin

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "sysfs-pwm"
-version = "0.1.0"
+version = "0.2.0-alpha.0"
 authors = [
     "Rust Embedded WG Linux Team <embedded-linux@teams.rust-embedded.org>",
     "Paul Osborne <osbpau@gmail.com>"