fix(tvix/boot/tests): set SSL_CERT_FILE

This is necessary for http clients to successfully construct.

Change-Id: If0d968e964f5c58d9956b92ee0ab3d97c39391d6
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11892
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: Connor Brewster <cbrewster@hey.com>
Tested-by: BuildkiteCI

tvix/boot/tests/default.nix

@@ -48,6 +48,8 @@ let
         ];
         buildCommand = ''
           touch $out
+          # Ensure we can construct http clients.
+          export SSL_CERT_FILE="${pkgs.cacert.out}/etc/ssl/certs/ca-bundle.crt"
 
           # Start the tvix daemon, listening on a unix socket.
           BLOB_SERVICE_ADDR=${blobServiceAddr} \