excluding env submodule in vendored riscv-tests as riscv-test-env is vendored separately

vendor/riscv_tests.lock.hjson

@@ -0,0 +1,14 @@
+// Copyright lowRISC contributors.
+// Licensed under the Apache License, Version 2.0, see LICENSE for details.
+// SPDX-License-Identifier: Apache-2.0
+
+// This file is generated by the util/vendor script. Please do not modify it
+// manually.
+
+{
+  upstream:
+  {
+    url: https://github.com/riscv-software-src/riscv-tests
+    rev: f163ddfc9b0bf78fb8180012ffcfc93427f780f0
+  }
+}

vendor/riscv_tests.vendor.hjson

@@ -9,4 +9,8 @@
     url: "https://github.com/riscv-software-src/riscv-tests",
     rev: "master",
   },
+  exclude_from_upstream: [
+    "env/",
+    "debug/programs/encoding.h"
+  ]
 }