Getting Bluesky posts is not public anymore and returns HTTP status `403`

[McPringle]

Running swiss.fihlon.apus.plugin.social.bluesky.DefaultBlueSkyLoaderTest:

Caused by: java.io.IOException: Server returned HTTP response code: 403 for URL: https://public.api.bsky.app/xrpc/app.bsky.feed.searchPosts?q=java
	at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:2013)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1614)
	at java.base/sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:223)
	at java.base/java.net.URL.openStream(URL.java:1325)
	at swiss.fihlon.apus.util.DownloadUtil.getString(DownloadUtil.java:31)
	at swiss.fihlon.apus.plugin.social.bluesky.DefaultBlueSkyLoader.getPosts(DefaultBlueSkyLoader.java:34)
	... 7 more