Appveyor build - skip irrelevant commits

Since we're only building on Windows, skip changes to debian directory
and to shell scripts.

appveyor.yml

@@ -27,4 +27,9 @@ test_script:
   - set /A parallel=4*%NUMBER_OF_PROCESSORS%
   - perl mysql-test-run.pl --force --max-test-fail=10 --retry=2 --parallel=%parallel% --testcase-timeout=4 --suite=main  --skip-test-list=unstable-tests --mysqld=--loose-innodb-flush-log-at-trx-commit=2
 
+skip_commits:
+  files:
+    - debian/
+    - '**/*.sh'
+
 image: Visual Studio 2022