Fix threading issue in observable cache. Fixes reactivemarbles#538 (r…

…eactivemarbles#539)

Co-authored-by: Glenn <5834289+glennawatson@users.noreply.github.com>

build(deps): bump Microsoft.NET.Test.Sdk from 16.11.0 to 17.0.0 in /s…

…rc (reactivemarbles#526)

Bumps [Microsoft.NET.Test.Sdk](https://github.com/microsoft/vstest) from 16.11.0 to 17.0.0.
- [Release notes](https://github.com/microsoft/vstest/releases)
- [Commits](microsoft/vstest@v16.11.0...v17.0.0)

---
updated-dependencies:
- dependency-name: Microsoft.NET.Test.Sdk
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Roland Pheasant <roland_pheasant@hotmail.com>

housekeeping: Release 7.4.x (reactivemarbles#521)

Bump version for release (reactivemarbles#503)

housekeeping: Release 7.2.x (reactivemarbles#487)

Ensure comparer changed is subscribed to before data changed for list. …

…Fixes reactivemarbles#473 (reactivemarbles#476)

build(deps): bump Nerdbank.GitVersioning from 3.3.37 to 3.4.194 in /s…

…rc (reactivemarbles#469)

Bumps [Nerdbank.GitVersioning](https://github.com/dotnet/Nerdbank.GitVersioning) from 3.3.37 to 3.4.194.
- [Release notes](https://github.com/dotnet/Nerdbank.GitVersioning/releases)
- [Commits](dotnet/Nerdbank.GitVersioning@v3.3.37...v3.4.194)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

housekeeping: Release 7.1.x (reactivemarbles#443)

housekeeping: Update the .gitignore file. (reactivemarbles#431)

Update ci-build.yml (reactivemarbles#430)