cygwin: disable CI until cygwin fix signal handling

cygwin 3.5.5 broke signal handling and broke CI.

To reduce noise disable cygwin CI for now.

Given the way the universe works, cygwin will be fixed immediately
after this is applied to blead.

Author: tonycoz

.github/workflows/testsuite.yml

@@ -563,13 +563,14 @@ jobs:
   # | (__| |_| | (_| |\ V  V /| | | | |
   #  \___|\__, |\__, | \_/\_/ |_|_| |_|
   #       |___/ |___/
+  # disabled until cygwin get a signal handling fix out
 
   cygwin:
     name: "cygwin"
     runs-on: windows-2019
     timeout-minutes: 120
     needs: sanity_check
-    if: (! cancelled() && (needs.sanity_check.outputs.run_all_jobs == 'true' || needs.sanity_check.outputs.ci_force_cygwin == 'true'))
+    if: (! cancelled() && (needs.sanity_check.outputs.ci_force_cygwin == 'true'))
 
     steps:
       # we use Cygwin git, so no need to configure git here.