Adjust container -- does it fix?

Signed-off-by: Larry Gritz <[email protected]>

Author: lgritz

.github/workflows/ci.yml

@@ -102,7 +102,7 @@ jobs:
           - desc: oldest everything gcc9/C++17 llvm9 py3.7 oiio2.5 no-simd
             nametag: linux-oldest
             runner: ubuntu-latest
-            container: aswftesting/ci-osl:2021-clang11
+            container: aswf/ci-osl:2021
             vfxyear: 2021
             old_node: 1
             cxx_std: 17