Testing git-secret

Adding a dummy, top-level secrets.json file using `git-secret`. It might be nice
to have a mono-secrets file in json because then I can use it with `jq` like:

```shell
$ jq '.secret' --join-output < ~/briefcase/secrets.json
```

1 files changed, 0 insertions, 0 deletions

diff --git a/secrets.json.secret b/secrets.json.secret
new file mode 100644
index 000000000000..9c3883238d85
--- /dev/null
+++ b/secrets.json.secret
Binary files differ