pyproject: bump swarmit to >= 0.8.0rc3

The OTA capture transport (request_lh2_capture / send_lh2_calibration)
lands in swarmit 0.8.0rc3; rc2 lacks those symbols, so it is the true
floor for `dotbot swarm lh2-calibration`.

AI-assisted: Claude Opus 4.8

Author: geonnave

pyproject.toml

@@ -50,7 +50,7 @@ dependencies = [
     "intelhex       >= 2.3.0",
     "marilib-pkg    >= 0.9.0rc3",
     "pydotbot-utils >= 0.3.0",
-    "swarmit        >= 0.8.0rc2",
+    "swarmit        >= 0.8.0rc3",
     "toml           >= 0.10.2",
     "tomlkit        >= 0.13.0",
 ]