recoll: 1.23.5 -> 1.23.7

Semi-automatic update. These checks were performed:

- built on NixOS
- ran `/nix/store/l9d50wqwzrfqgj3wj9456kiapygmacr0-recoll-1.23.7/bin/recollindex -h` got 0 exit code
- ran `/nix/store/l9d50wqwzrfqgj3wj9456kiapygmacr0-recoll-1.23.7/bin/recollindex -h` and found version 1.23.7
- found 1.23.7 with grep in /nix/store/l9d50wqwzrfqgj3wj9456kiapygmacr0-recoll-1.23.7
- found 1.23.7 in filename of file in /nix/store/l9d50wqwzrfqgj3wj9456kiapygmacr0-recoll-1.23.7

cc "@jcumming"