Bump System.Memory from 4.5.3 to 4.5.4 (#757)

Bumps [System.Memory](https://github.com/dotnet/corefx) from 4.5.3 to 4.5.4.
- [Release notes](https://github.com/dotnet/corefx/releases)
- [Commits](https://github.com/dotnet/corefx/commits)

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

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

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

Author: dependabot[bot]

src/Core/Silk.NET.Core/Silk.NET.Core.csproj

@@ -10,7 +10,7 @@
         <PackageReference Include="Microsoft.CSharp" Version="4.7.0" />
         <PackageReference Include="Microsoft.DotNet.PlatformAbstractions" Version="3.1.6" />
         <PackageReference Include="Microsoft.Extensions.DependencyModel" Version="3.1.1" />
-        <PackageReference Include="System.Memory" Version="4.5.3" />
+        <PackageReference Include="System.Memory" Version="4.5.4" />
         <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="4.7.0" />
         <PackageReference Include="System.Numerics.Vectors" Version="4.5.0" />
     </ItemGroup>

src/Lab/Experiments/PrototypeStructChaining/PrototypeStructChaining/PrototypeStructChaining.csproj

@@ -13,7 +13,7 @@
         <PackageReference Include="Microsoft.DotNet.PlatformAbstractions" Version="3.1.6" />
         <PackageReference Include="Microsoft.Extensions.DependencyModel" Version="3.1.1" />
         <PackageReference Include="Silk.NET.Core" Version="2.9.0" />
-        <PackageReference Include="System.Memory" Version="4.5.3" />
+        <PackageReference Include="System.Memory" Version="4.5.4" />
         <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="4.7.0" />
         <PackageReference Include="System.Numerics.Vectors" Version="4.5.0" />
     </ItemGroup>