CI: SSL: use proper version generating when "latest" semantic is used

both "OPENSSL_VERSION=latest" and "LIBRESSL_VERSION=latest" processing
introduced errors when build-ssl.sh script was invoked. that error
in turn led to skipping custom openssl build and haproxy was linked against
stock openssl, i.e. openssl-1.1.1

(cherry picked from commit 14711bdc9a0586fc54df25532b51b8b629dd78ef)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit b78d3e859503ccbf36db258a82b910232ee70ade)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 0e35d501382c3e9c35d03aac70a3d1dcd6bd9779)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
diff --git a/.github/matrix.py b/.github/matrix.py
index d2b37cb..14d3b5e 100644
--- a/.github/matrix.py
+++ b/.github/matrix.py
@@ -41,7 +41,7 @@
         if "openssl-" in name:
             if name > latest_tag:
                latest_tag = name
-    return "OPENSSL={}".format(latest_tag[8:])
+    return "OPENSSL_VERSION={}".format(latest_tag[8:])
 
 def determine_latest_libressl(ssl):
     libressl_download_list = urllib.request.urlopen("http://ftp.openbsd.org/pub/OpenBSD/LibreSSL/")
@@ -49,7 +49,7 @@
         decoded_line = line.decode("utf-8")
         if "libressl-" in decoded_line and ".tar.gz.asc" in decoded_line:
              l = re.split("libressl-|.tar.gz.asc", decoded_line)[1]
-    return "LIBRESSL={}".format(l)
+    return "LIBRESSL_VERSION={}".format(l)
 
 def clean_compression(compression):
     return compression.replace("USE_", "").lower()