remove 1.9-nightly CI

Author: aplavin

.github/workflows/CI.yml

@@ -19,7 +19,6 @@ jobs:
           - '1.6'
           - '1.7'
           - '1'
-          - '1.9-nightly'
           - 'nightly'
         os:
           - ubuntu-latest

.github/workflows/Downstream.yml

@@ -10,7 +10,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        julia-version: [1.6, 1, 1.9-nightly, nightly]
+        julia-version: [1.6, 1, nightly]
         os: [ubuntu-latest]
         package:
           - {repo: JuliaObjects/Accessors.jl}