Couldn't get "sfText_getLineSpacing" from "libcsfml-graphics.so"

Distro: Ubuntu Focal Fossa
Arch: x86_64
Package: libcsfml-graphics2.5 version 2.5-1build1

Problem: the library does not export the function sfText_getLineSpacing, which it should. This prevents code using the library from working fully (or in my case, at all).

As I understand it, this is a known problem, and has been fixed upstream in CSFML. See:

https://github.com/massung/r-cade/issues/5
https://r-cade.io/faq
https://github.com/SFML/CSFML/pull/130/files

To replicate, in my case:
- apt-get install racket libcsfml-*
- raco pkg install r-cade
- create a file test.rkt
- paste into it the music example from tutorial page here: https://r-cade.io/tutorials
- Run it using `racket test.rkt`

For completeness, the example code is:

```
    (require r-cade)

    ;; create a song
    (define theme
      (music "E4-B3C4D-CB3A-AC4E-DCB3-C4D-E-C-A3-A-.D4-FA-GFE-CE-DCB3-BC4D-E-C-A3-A-."
             #:tempo 280))

    (define (game-loop)
      (text 2 2 "Playing the Tetris theme song.")
      (wait)
      (quit))

    (define (start-music)
      (play-music theme))

    (run game-loop 128 128 #:init start-music)
```

This fails unexpectedly with the following output:

```
ffi-obj: couldn't get "sfText_getLineSpacing" from "libcsfml-graphics.so" (/lib/x86_64-linux-gnu/libcsfml-graphics.so: undefined symbol: sfText_getLineSpacing)
  context...:
   /usr/share/racket/collects/ffi/../racket/private/more-scheme.rkt:261:28
   /usr/share/racket/collects/ffi/unsafe.rkt:216:2: get-ffi-obj*
   "/home/nick/.racket/7.2/pkgs/csfml/graphics.rkt": [running body]
   temp37_0
   for-loop
   run-module-instance!125
   for-loop
   [repeats 1 more time]
   run-module-instance!125
   for-loop
   [repeats 1 more time]
   run-module-instance!125
   for-loop
   [repeats 1 more time]
   run-module-instance!125
   perform-require!78
```