layer.conf: switch to nanbield series

Since oe-core switched to `nanbield` release series only (i.e. removed
`mickledore` compatiblity), we have to update our `layer.conf` file.

Signed-off-by: Jean-Pierre Geslin <jarsop@outlook.com>
Signed-off-by: Enrico Jorns <ejo@pengutronix.de>

conf/layer.conf

@@ -17,7 +17,7 @@ LAYERRECOMMENDS_rauc = "meta-python"
 # meta-filesystems is needed to build cascync with fuse support (the default)
 LAYERRECOMMENDS_rauc += "meta-filesystems"
 
-LAYERSERIES_COMPAT_rauc = "mickledore"
+LAYERSERIES_COMPAT_rauc = "nanbield"
 
 # Sanity check for meta-rauc layer.
 # Setting SKIP_META_RAUC_FEATURE_CHECK to "1" would skip the bbappend files check.