feat(deps): Bump singer-sdk in the singer-sdk group

Bumps the singer-sdk group with 1 update: [singer-sdk](https://github.com/meltano/sdk).


Updates `singer-sdk` from 0.39.1 to 0.40.0
- [Release notes](https://github.com/meltano/sdk/releases)
- [Changelog](https://github.com/meltano/sdk/blob/main/CHANGELOG.md)
- [Commits](meltano/sdk@v0.39.1...v0.40.0)

---
updated-dependencies:
- dependency-name: singer-sdk
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: singer-sdk
...

Signed-off-by: dependabot[bot] <support@github.com>

pyproject.toml

@@ -37,12 +37,12 @@ keywords = [
 python = ">=3.8"
 colorama = "==0.4.*"
 requests-cache = "==1.2.*"
-singer-sdk = "==0.39.*"
+singer-sdk = "==0.40.*"
 structlog = "==24.4.*"
 
 [tool.poetry.group.dev.dependencies]
 pytest = "==8.*"
-singer-sdk = { version = "==0.39.*", extras = [
+singer-sdk = { version = "==0.40.*", extras = [
   "testing",
 ] }