Incorrect content-type for some conda-forge repodata

[katzj]

I happened to notice that some of the repodata.json files (such as https://conda.anaconda.org/conda-forge/linux-armv7l/repodata.json and https://conda.anaconda.org/conda-forge/linux-32/repodata.json) are returning a Content-Type of binary/octet-stream instead of application/json which makes it so that HTTP libraries don't do the right thing knowing it's json and parsing accordingly. I've worked around it in my code but probably worth fixing for others who may similarly be looking at this metadata.