eo_debian: don't crash on bullseye/sid in /etc/debian_version (#50377)

prometheus-entrouvert-exporter/prometheus-entrouvert-exporter.py

@@ -49,7 +49,11 @@ def run(cmd):
 
 def debian(ctn):
     with open('/etc/debian_version') as fh:
-        ve = float(fh.read().strip())
+        content = fh.read()
+        if 'sid' in content:
+            ve = 9999
+        else:
+            ve = float(content.strip())
         eo_debian.labels(ctn).set(ve)