Merge pull request #23 from troibe/https-riscv-test-env

Use https for riscv-test-env submodule instead of ssh auth

.gitmodules

@@ -1,3 +1,3 @@
 [submodule "env/riscv-test-env"]
 	path = env/riscv-test-env
-	url = git@github.com:riscv/riscv-test-env.git
+	url = https://github.com/riscv/riscv-test-env.git