[Git][ocaml-team/unison][2.53/debian] 6 commits: Switch debian/watch to version 5

1fbab046
by Stephane Glondu at 2025-12-01T10:15:49+01:00
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Switch debian/watch to version 5
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a599d37d
by Stephane Glondu at 2025-12-01T10:16:16+01:00
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New upstream version 2.53.8
```

ae8878c4

by Stephane Glondu at 2025-12-01T10:16:21+01:00

Update upstream source from tag 'upstream/2.53.8'

Update to upstream version '2.53.8'
with Debian dir dc3c255dcf3d25d5dd2f2224ce02aa4a815ff025

5e448d42
by Stephane Glondu at 2025-12-01T10:16:25+01:00
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New upstream release
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509dc2da
by Stephane Glondu at 2025-12-01T10:20:35+01:00
```
Update packaging
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8c134fe4
by Stephane Glondu at 2025-12-01T10:20:35+01:00
```
Update changelog and prepare upload to unstable
```