fix(ci): remove stray digibyte submodule gitlink breaking actions/checkout

[DennisPitallano]

Problem

actions/checkout@v4 fails on this repo with:

fatal: No url found for submodule path 'digibyte' in .gitmodules
Error: The process '/usr/bin/git' failed with exit code 128

Example failing run: https://github.com/DigiByte-Core/DigiByte.org/actions/runs/30958026357

Root cause

The repo's tree contains a submodule gitlink at path digibyte (mode 160000, pinned to 8a3fd47b943ff883e51bf988dc9bac92916274dc) but no matching .gitmodules file at the root. So whenever actions/checkout runs git submodule update --init --recursive it can't resolve a URL for the digibyte path and aborts.

Verified with:

$ git ls-tree HEAD digibyte
160000 commit 8a3fd47b943ff883e51bf988dc9bac92916274dc	digibyte
$ git ls-tree HEAD .gitmodules   # empty

The gitlink was introduced accidentally (likely because a nested .git was present inside a local digibyte/ working copy at git add time). The DigiByte Core source isn't part of the Jekyll website, so the gitlink is just dangling data.

Fix

• Remove the stray digibyte gitlink from the tree (git rm --cached digibyte).
• Add digibyte/ to .gitignore so a local Core source checkout can't be re-added accidentally.

Diff is only 2 files: .gitignore (+3) and removal of the digibyte gitlink entry.

Impact

• Unblocks CI / Pages workflows that use submodules: true or submodules: recursive.
• No user-visible / site-content change.
• Local digibyte/ working directories on contributors' machines are untouched (only the index entry is removed).

Note on the "Node 20 deprecation" banner

The Node 20 is being deprecated line in the failing log is unrelated runner-level info and did not cause the failure.

[bastiandriessen]

Approve

This correctly fixes the broken submodule reference that is currently blocking all GitHub Pages deployments.

The analysis and the two-line change (git rm --cached digibyte + adding digibyte/ to .gitignore) are accurate and minimal.

Once this lands, the redesigned site will go live.

Ready to merge from me.

[ycagel]

cACK