patch 9.0.0596: CI on Mac M1 has the channel feature disabled

Problem:    CI on Mac M1 has the channel feature disabled.
Solution:   Include the channel feature.
diff --git a/.cirrus.yml b/.cirrus.yml
index 33863a3..a1f055b 100644
--- a/.cirrus.yml
+++ b/.cirrus.yml
@@ -37,7 +37,7 @@
     - brew install gettext libtool
   build_script:
     - NPROC=$(getconf _NPROCESSORS_ONLN)
-    - ./configure --with-features=${FEATURES} --disable-channel
+    - ./configure --with-features=${FEATURES}
     - make -j${NPROC} CC=clang
   test_script:
     - src/vim --version
diff --git a/src/version.c b/src/version.c
index 35f37e9..3111b4f 100644
--- a/src/version.c
+++ b/src/version.c
@@ -700,6 +700,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    596,
+/**/
     595,
 /**/
     594,