CI: Github Actions: temporarily disable BoringSSL builds

A recent update to BoringSSL broke the build again, and given that
it's not used except for QUIC development, let's temporarily disable
it until the issue is analysed and fixed.

(cherry picked from commit 30ee2965b66f20a2649323ca36029bf2440e34b9)
Signed-off-by: William Lallemand <wlallemand@haproxy.org>
diff --git a/.github/matrix.py b/.github/matrix.py
index 067ce93..9900314 100644
--- a/.github/matrix.py
+++ b/.github/matrix.py
@@ -106,7 +106,7 @@
         "OPENSSL_VERSION=1.0.2u",
         "LIBRESSL_VERSION=2.9.2",
         "LIBRESSL_VERSION=3.3.3",
-        "BORINGSSL=yes",
+#        "BORINGSSL=yes",
     ]:
         flags = ["USE_OPENSSL=1"]
         if ssl == "BORINGSSL=yes":