remove unsuded .gitmodules

.gitmodules

@@ -1,10 +0,0 @@
-
-[submodule "tests/shell/bats"]
-	path = tests/shell/bats
-	url = https://github.com/bats-core/bats-core.git
-[submodule "tests/shell/test_helper/bats-support"]
-	path = tests/shell/test_helper/bats-support
-	url = https://github.com/bats-core/bats-support.git
-[submodule "tests/shell/test_helper/bats-assert"]
-	path = tests/shell/test_helper/bats-assert
-	url = https://github.com/bats-core/bats-assert.git