test-template: fix stdio mode on Windows

Otherwise, CBOR data would be corrupted. Spotted by Matt Harbison.

tests/test-template-functions.t

@@ -1499,11 +1499,15 b' Test cbor filter:'
 
   $ cat <<'EOF' > "$TESTTMP/decodecbor.py"
   > from __future__ import absolute_import
-  > from mercurial import pycompat
+  > from mercurial import (
+  >     dispatch,
+  >     pycompat,
+  > )
   > from mercurial.utils import (
   >     cborutil,
   >     stringutil,
   > )
+  > dispatch.initstdio()
   > items = cborutil.decodeall(pycompat.stdin.read())
   > pycompat.stdout.write(stringutil.pprint(items, indent=1) + b'\n')
   > EOF

tests/test-template-map.t

@@ -673,11 +673,15 b' test CBOR style:'
 
   $ cat <<'EOF' > "$TESTTMP/decodecborarray.py"
   > from __future__ import absolute_import
-  > from mercurial import pycompat
+  > from mercurial import (
+  >     dispatch,
+  >     pycompat,
+  > )
   > from mercurial.utils import (
   >     cborutil,
   >     stringutil,
   > )
+  > dispatch.initstdio()
   > data = pycompat.stdin.read()
   > # our CBOR decoder doesn't support parsing indefinite-length arrays,
   > # but the log output is indefinite stream by nature.