DRIVERS-3110 Follow up for Kondukto migration

[blink1073]

• Update the sbom file to get a new serialNumber. This is required for each version of the software
• Mark usages of SILK_ASSET_GROUP for removal in V3
• Update go action to use sbom_in_path instead of SILK_ASSET_GROUP
• Update create-branch action to remove handling of SILK_ASSET_GROUP
• Update the readme

[blink1073]

Tested with motor: https://github.com/mongodb/motor/actions/runs/13502258761

[blink1073]

Testing again with --generate-new-serial-number flag...

[blink1073]

Passing test: https://github.com/mongodb/motor/actions/runs/13503055139/job/37726241258

Generating new serial number and setting SBOM version to '1'