build: Added -e to sed command for mac specific version

Author: mediumTaj

.travis.yml

@@ -13,7 +13,7 @@ git:
   submodules: false
 before_install:
 # Use sed to replace the SSH URL with the public URL, then initialize submodules
-- sed -i 's/[email protected]:/https:\/\/github.com\//' .gitmodules
+- sed -i -e 's/[email protected]:/https:\/\/github.com\//' .gitmodules
 - git submodule update --init --recursive
 - chmod a+x ./Travis/installUnity.sh
 - npm install -g [email protected]