Upgrade LibGit2Sharp to 0.26.0-preview-0070

[magne]

Part of fix for GitTools/GitVersion#1483 and GitTools/GitVersion#1511. Not strictly necessary, but would require adding a direct dependency from GitTools/GitVersion to libgit2/libgit2sharp.

Checklist

• I have included examples or tests
• I have updated the change log
• I am listed in the CONTRIBUTORS file
• I have cleaned up the commit history (use rebase and squash)

Changes proposed in this pull request:

• Upgrade LibGit2Sharp from version 0.25.0-preview-0033 to 0.26.0-preview-0070.
• Remove target net40 and retarget net45 to net461 since LibGit2Sharp now targets these frameworks.
• Retarget netstandard1.3 to netstandard2.0 since LibGit2Sharp now targets this framework.
• Fix src/GitTools.Core/Git/DynamicRepositories.cs so that it handles a trailing directory separator.
• Fix tests in src/GitTools.Core.Tests/Git/DynamicRepositoriesTests.cs so that it handles trailing directory separators and runs green under linux.

[asbjornu]

I'm not sure how relevant this is after GitTools/GitVersion#1581. The upgrade to LibGit2Sharp 0.26 was done in GitTools/GitVersion#1713, so that supersedes this PR unless you want to use GitTools.Core directly. That poses the question: Should we just archive this repository altogether? Thoughts, @arturcic?

@magne, can you please try the latest build of GitVersion and see if it works for you?

[arturcic]

I'm not sure how relevant this is after GitTools/GitVersion#1581. The upgrade to LibGit2Sharp 0.26 was done in GitTools/GitVersion#1713, so that supersedes this PR unless you want to use GitTools.Core directly. That poses the question: Should we just archive this repository altogether? Thoughts, @arturcic?

@magne, can you please try the latest build of GitVersion and see if it works for you?

GitTools.Core is now integrated into GitVersion itself. I think we could archive the repo as it is really outdated, and it's targeting .NETStandard 1.3. The latest version we shipped was 2 years ago.

[asbjornu]

I agree. We should probably edit the README file to explain why the repository is archived. I'll get to it.