use macos-13 builders; macos-12 EOL (#6602)

.github/workflows/ci.yml

@@ -52,7 +52,7 @@ jobs:
             builder: ['self-hosted','ubuntu-22.04']
           - target:
               os: macos
-            builder: macos-12
+            builder: macos-13
           - target:
               os: windows
             builder: windows-2019

.github/workflows/cron.yml

@@ -26,10 +26,10 @@ jobs:
             cpu: amd64
           - os: windows
             cpu: amd64
-        branch: [upstream/version-1-6, upstream/devel]
+        branch: [upstream/version-2-0, upstream/devel]
         include:
-          - branch: upstream/version-1-6
-            branch-short: version-1-6
+          - branch: upstream/version-2-0
+            branch-short: version-2-0
           - branch: upstream/devel
             branch-short: devel
             nimflags-extra: --mm:refc
@@ -39,7 +39,7 @@ jobs:
             shell: bash
           - target:
               os: macos
-            builder: macos-11
+            builder: macos-13
             shell: bash
           - target:
               os: windows