Bump Microsoft.Build.Tasks.Core and Microsoft.Build.Utilities.Core (#549)

Bumps Microsoft.Build.Tasks.Core from 18.6.3 to 18.7.1
Bumps Microsoft.Build.Utilities.Core from 18.6.3 to 18.7.1

---
updated-dependencies:
- dependency-name: Microsoft.Build.Tasks.Core
  dependency-version: 18.7.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: Microsoft.Build.Utilities.Core
  dependency-version: 18.7.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

src/dotnes.tasks/dotnes.tasks.csproj

@@ -15,8 +15,8 @@
     <Using Include="Microsoft.Build.Utilities" />
     <Using Include="NES" />
     <InternalsVisibleTo Include="dotnes.tests" />
-    <PackageReference Include="Microsoft.Build.Tasks.Core" Version="18.6.3" />
-    <PackageReference Include="Microsoft.Build.Utilities.Core" Version="18.6.3" />
+    <PackageReference Include="Microsoft.Build.Tasks.Core" Version="18.7.1" />
+    <PackageReference Include="Microsoft.Build.Utilities.Core" Version="18.7.1" />
     <PackageReference Include="System.Reflection.Metadata" Version="10.0.9" />
     <None Update="Targets\*" CopyToOutputDirectory="PreserveNewest" TargetPath="%(FileName)%(Extension)" />
   </ItemGroup>