[DRE-maint] Bug#1123650: Acknowledgement (schleuder installation fails)

[Andrew Gallagher]

This seems to be because:

* schleuder depends directly on both thin~>1 and sinatra>=3.1
* thin 1.8.2 depends on rack < 3
* trixie ships with sinatra 4.1.1, which depends on rack >= 3
* conflict

I attempted to fix this by forcibly downgrading sinatra and rack:

```
apt install ruby-sinatra=3.0.5-3 ruby-rack=2.2.13-1~deb12u1 
ruby-rack-protection=3.0.5-3
```

This however forcibly removed schleuder. On reinstalling schleuder, 
sinatra and rack were upgraded to the conflicting versions again:

```
root at fum:/etc/schleuder# apt install schleuder
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following additional packages will be installed:
   ruby-rack ruby-rack-protection ruby-rack-session ruby-rackup 
ruby-sinatra ruby-sinatra-contrib
The following NEW packages will be installed:
   ruby-rack-session ruby-rackup ruby-sinatra-contrib schleuder
The following packages will be upgraded:
   ruby-rack ruby-rack-protection ruby-sinatra
3 upgraded, 4 newly installed, 0 to remove and 586 not upgraded.
Need to get 0 B/439 kB of archives.
After this operation, 597 kB of additional disk space will be used.
Do you want to continue? [Y/n]
(Reading database ... 74323 files and directories currently installed.)
Preparing to unpack .../0-ruby-rack-protection_4.1.1-5_all.deb ...
Unpacking ruby-rack-protection (4.1.1-5) over (3.0.5-3) ...
Preparing to unpack .../1-ruby-sinatra_4.1.1-5_all.deb ...
Unpacking ruby-sinatra (4.1.1-5) over (3.0.5-3) ...
Preparing to unpack .../2-ruby-rack_3.1.18-1~deb13u1_all.deb ...
Unpacking ruby-rack (3.1.18-1~deb13u1) over (2.2.13-1~deb12u1) ...
Selecting previously unselected package ruby-rack-session.
Preparing to unpack .../3-ruby-rack-session_2.1.1-0.1_all.deb ...
Unpacking ruby-rack-session (2.1.1-0.1) ...
Selecting previously unselected package ruby-rackup.
Preparing to unpack .../4-ruby-rackup_2.1.0-4_all.deb ...
Unpacking ruby-rackup (2.1.0-4) ...
Selecting previously unselected package ruby-sinatra-contrib.
Preparing to unpack .../5-ruby-sinatra-contrib_4.1.1-5_all.deb ...
Unpacking ruby-sinatra-contrib (4.1.1-5) ...
Selecting previously unselected package schleuder.
Preparing to unpack .../6-schleuder_5.0.1-2_all.deb ...
Unpacking schleuder (5.0.1-2) ...
Setting up ruby-rack (3.1.18-1~deb13u1) ...
Setting up ruby-rack-session (2.1.1-0.1) ...
Setting up ruby-rack-protection (4.1.1-5) ...
Setting up ruby-rackup (2.1.0-4) ...
Setting up ruby-sinatra (4.1.1-5) ...
Setting up ruby-sinatra-contrib (4.1.1-5) ...
Setting up schleuder (5.0.1-2) ...
```

And schleuder-api-daemon refuses to start up again.

Schleuder is therefore technically uninstallable due to a gem dependency 
conflict, although some basic functions do work because they do not 
depend on thin.