MINOR: checks: Support HTTP/2 version (without '.0') for http-check send rules

The version is partially parsed to set the flag HTX_SL_F_VER_11 on the HTX
message. But exactly 8 chars is expected. So if "HTTP/2" is specified, the flag
is not set. Thus, the version parsing has been updated to handle "HTTP/2" and
"HTTP/2.0" the same way.
diff --git a/src/checks.c b/src/checks.c
index 36aa718..0b934b6 100644
--- a/src/checks.c
+++ b/src/checks.c
@@ -1916,8 +1916,8 @@
 		uri = (isttest(send->http.uri) ? send->http.uri : ist("/")); // TODO: handle uri_fmt
 		vsn = (isttest(send->http.vsn) ? send->http.vsn : ist("HTTP/1.0"));
 
-		if (istlen(vsn) == 8 &&
-		    (*(vsn.ptr+5) > '1' || (*(vsn.ptr+5) == '1' && *(vsn.ptr+7) >= '1')))
+		if ((istlen(vsn) == 6 && *(vsn.ptr+5) == '2') ||
+		    (istlen(vsn) == 8 && (*(vsn.ptr+5) > '1' || (*(vsn.ptr+5) == '1' && *(vsn.ptr+7) >= '1'))))
 			slflags |= HTX_SL_F_VER_11;
 		slflags |= (HTX_SL_F_XFER_LEN|HTX_SL_F_CLEN);
 		if (!isttest(send->http.body))