Fix the format of /etc/os-release

The os-release crate can't handle parsing the current format, and the
python example on the /etc/os-release man page suggests that it is
invalid to have a space before the equal sign.

config/base.toml

@@ -40,8 +40,8 @@ redox
 [[files]]
 path = "/usr/lib/os-release"
 data = """
-PRETTY_NAME = "Redox OS 0.8.0"
-NAME = "Redox OS"
+PRETTY_NAME="Redox OS 0.8.0"
+NAME="Redox OS"
 VERSION_ID="0.8.0"
 VERSION="0.8.0"
 ID="redox-os"