build/OWNERS: Add Dan and Sascha as reviewers

Dan and Sascha are senior Release Managers, SIG Release leadership, and
have already been giving thoughtful reviews of the content in this
directory.

Adding them as reviewers to spread the load of SIG Release eyes on
content.

Signed-off-by: Stephen Augustus <foo@auggie.dev>

build/OWNERS

@@ -5,8 +5,10 @@ reviewers:
   - cblecker
   - dims
   - fejta
-  - justaugustus
+  - hasheddan # Release Manager / SIG Technical Lead
+  - justaugustus # Release Manager / SIG Chair
   - lavalamp
+  - saschagrunert # Release Manager / SIG Chair
   - spiffxp
 approvers:
   - bentheelder