port generate-recipes.py to python3

Directly via 2to3 seems to work without issues. Porting since it's part
of the lnst-recipes package in Fedora and it's making the package depend
on python2.

Signed-off-by: Ondrej Lichtner <olichtne@redhat.com>

v15 version release

This will be the final release of LNST that works with legacy XML
recipes and on python3.

Signed-off-by: Ondrej Lichtner <olichtne@redhat.com>

v14 version release

This will be the final release of LNST that works with legacy XML
recipes and on python2.

Signed-off-by: Ondrej Lichtner <olichtne@redhat.com>

13 release

Signed-off-by: Jan Tluka <jtluka@redhat.com>

12 release

Signed-off-by: Ondrej Lichtner <olichtne@redhat.com>

11 release

Signed-off-by: Ondrej Lichtner <olichtne@redhat.com>

10 release

Signed-off-by: Ondrej Lichtner <olichtne@redhat.com>

9 release

Signed-off-by: Ondrej Lichtner <olichtne@redhat.com>

8 release

Signed-off-by: Jiri Pirko <jiri@resnulli.us>

7 release

Signed-off-by: Jiri Pirko <jiri@resnulli.us>