Updated target framework versions

Author: lord-executor

.travis.yml

@@ -1,9 +1,9 @@
 language: csharp
 mono: none
-dotnet: 2.1.500
+dotnet: 3.1
 solution: src/MaybeSharp.sln
 script:
   - dotnet restore src/MaybeSharp.sln
-  - dotnet build src/MaybeSharp.sln -f netcoreapp2.1
-  - dotnet test src/MaybeSharp.sln -f netcoreapp2.1
-  - dotnet test src/MaybeSharp.sln -f netcoreapp2.1 /p:CollectCoverage=true /p:Include="[MaybeSharp]*"
+  - dotnet build src/MaybeSharp.sln -f netcoreapp3.1
+  - dotnet test src/MaybeSharp.sln -f netcoreapp3.1
+  - dotnet test src/MaybeSharp.sln -f netcoreapp3.1 /p:CollectCoverage=true /p:Include="[MaybeSharp]*"

src/MaybeSharp.UnitTests/MaybeSharp.UnitTests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp2.1</TargetFramework>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>

src/MaybeSharp/MaybeSharp.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>netcoreapp2.1;net46</TargetFrameworks>
+    <TargetFrameworks>netcoreapp2.1;netcoreapp3.1;net48</TargetFrameworks>
     <PackageProjectUrl>https://github.com/lord-executor/MaybeSharp</PackageProjectUrl>
     <PackageLicenseUrl>https://github.com/lord-executor/MaybeSharp/blob/master/LICENSE</PackageLicenseUrl>
     <RepositoryUrl>https://github.com/lord-executor/MaybeSharp</RepositoryUrl>