Bump HeterogeneousCollections from 1.0.3 to 1.0.4 in /ShapeSifter (#14)

Bumps [HeterogeneousCollections](https://github.com/G-Research/HeterogeneousCollections) from 1.0.3 to 1.0.4.
- [Release notes](https://github.com/G-Research/HeterogeneousCollections/releases)
- [Commits](G-Research/HeterogeneousCollections@HeterogeneousCollections.1.0.3...HeterogeneousCollections.1.0.4)

---
updated-dependencies:
- dependency-name: HeterogeneousCollections
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Patrick Stevens <3138005+Smaug123@users.noreply.github.com>

ShapeSifter/ShapeSifter.fsproj

@@ -45,7 +45,7 @@
 
   <ItemGroup>
     <PackageReference Update="FSharp.Core" Version="4.5.0" />
-    <PackageReference Include="HeterogeneousCollections" Version="1.0.3" />
+    <PackageReference Include="HeterogeneousCollections" Version="1.0.4" />
   </ItemGroup>
 
 </Project>