Bump JetBrains.Annotations from 2021.1.0 to 2021.3.0 (#1643)

Bumps [JetBrains.Annotations](https://github.com/JetBrains/JetBrains.Annotations) from 2021.1.0 to 2021.3.0.
- [Release notes](https://github.com/JetBrains/JetBrains.Annotations/releases)
- [Commits](https://github.com/JetBrains/JetBrains.Annotations/commits)

---
updated-dependencies:
- dependency-name: JetBrains.Annotations
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

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

Author: dependabot[bot]

src/Directory.Build.props

@@ -22,7 +22,7 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All"/>
     <PackageReference Include="MinVer" Version="2.5.0" PrivateAssets="All"/>
-    <PackageReference Include="JetBrains.Annotations" Version="2021.1.0" PrivateAssets="All"/>
+    <PackageReference Include="JetBrains.Annotations" Version="2021.3.0" PrivateAssets="All"/>
     <PackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.2" PrivateAssets="All" />
   </ItemGroup>