Bump log4net from 2.0.12 to 3.0.4

Bumps [log4net](https://github.com/apache/logging-log4net) from 2.0.12 to 3.0.4.
- [Release notes](https://github.com/apache/logging-log4net/releases)
- [Commits](apache/logging-log4net@rel/2.0.12...rel/3.0.4)

---
updated-dependencies:
- dependency-name: log4net
  dependency-version: 3.0.4
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

MyNumberNET_CLI/MyNumberNET_CLI.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <OutputType>Exe</OutputType>
     <TargetFramework>netcoreapp3.1</TargetFramework>
@@ -22,7 +22,7 @@
     </None>
   </ItemGroup>
   <ItemGroup>
-    <PackageReference Include="log4net" Version="2.0.12" />
+    <PackageReference Include="log4net" Version="3.0.4" />
     <PackageReference Include="System.Console" Version="4.3.1" />
     <PackageReference Include="System.Net.Sockets" Version="4.3.0" />
   </ItemGroup>