CI: use blacksail branches

OpenEmbedded Core is preparing to release and master has diverged. Until
we have also diverged, stick to the stable branches for oe-core and
bitbake.

meta-oe and meta-secure-core have not yet diverged, so they need to stay
on master for now.

Signed-off-by: Ross Burton <ross.burton@arm.com>

ci/base.yml

@@ -7,11 +7,12 @@ distro: poky
 
 defaults:
   repos:
-    branch: master
+    branch: blacksail
 
 repos:
   bitbake:
     url: https://git.openembedded.org/bitbake
+    branch: "2.20"
     layers:
       bitbake: disabled
 

ci/meta-openembedded.yml

@@ -6,6 +6,7 @@ header:
 repos:
   meta-openembedded:
     url: https://git.openembedded.org/meta-openembedded
+    branch: master
     layers:
       meta-filesystems:
       meta-networking:

ci/meta-secure-core.yml

@@ -6,6 +6,7 @@ header:
 repos:
   meta-secure-core:
     url: https://github.com/Wind-River/meta-secure-core.git
+    branch: master
     layers:
       meta-secure-core-common:
       meta-signing-key: