Remove notification settings from appveyor.yml

Notifications can be (and should be) configured on account basis on
the CI web site.  This avoids getting emails to openssl-commits for
personal accounts that also build OpenSSL stuff.
Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3484)

appveyor.yml

@@ -62,11 +62,3 @@ test_script:
             cmd /c "nmake install install_docs DESTDIR=..\_install 2>&1"
         }
     - cd ..
-
-notifications:
-    - provider: Email
-      to:
-          - openssl-commits@openssl.org
-      on_build_success: false
-      on_build_failure: true
-      on_build_status_changed: true