pw_env_setup: use CRLF on Windows

Switches the bootstrap/activate batch scripts to use CRLF on windows, as
just LF breaks things.

Change-Id: Icbc74a2ba03df80a44c185eea83d7fa3463bdd6c
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/23745
Reviewed-by: Rob Mohr <mohrr@google.com>
Commit-Queue: Armando Montanez <amontanez@google.com>
diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 0000000..a9a504a
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1,2 @@
+# Force batch scripts to use CRLF.
+*.bat text eol=crlf