ingest/fetch-ncov-global-case-counts: follow redirection

Our case counts updates resulted in an empty file¹, which lead to
the failure of our model pipelines.² Turns out the OWID endpoint is
redirected to another endpoint.

```
$ curl -I https://covid.ourworldindata.org/data/owid-covid-data.csv
HTTP/2 302
date: Fri, 27 Oct 2023 17:34:37 GMT
location: https://covid-19.nyc3.digitaloceanspaces.com/public/owid-covid-data.csv
...
```

curl does not follow HTTP redirections by default, so we have to tell
curl to follow redirection with `--location` option.

¹ https://github.com/nextstrain/forecasts-ncov/actions/runs/6656776373/job/18090077156#step:5:11
² https://bedfordlab.slack.com/archives/C03BY4MPNCS/p1698393532650979

ingest/bin/fetch-ncov-global-case-counts

@@ -3,7 +3,7 @@ set -euo pipefail
 
 # Fetch CSV from Our World in Data
 curl https://covid.ourworldindata.org/data/owid-covid-data.csv \
-    --fail --silent --show-error \
+    --fail --silent --show-error --location \
     --header 'User-Agent: https://github.com/nextstrain/counts ([email protected])' |
     # Only keep the date, location, and new_cases columns
     csvtk cut -f location,date,new_cases |