drop Git 2.15 test, that version is 10 years old

Author: linkdata

.github/workflows/self-test.yml

@@ -130,75 +130,3 @@ jobs:
         run: |
           set -euo pipefail
           test "${{ steps.detached_tag.outcome }}" = "failure"
-
-  git-2-15-compat:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Check out action source
-        uses: actions/checkout@v4
-        with:
-          path: action-src
-
-      - name: Install Git 2.15.0
-        shell: bash
-        run: |
-          set -euo pipefail
-
-          sudo apt-get update
-          sudo apt-get install -y \
-            build-essential \
-            gettext \
-            libcurl4-openssl-dev \
-            libexpat1-dev \
-            libssl-dev \
-            zlib1g-dev
-
-          curl -fsSL https://www.kernel.org/pub/software/scm/git/git-2.15.0.tar.xz -o git-2.15.0.tar.xz
-          tar -xf git-2.15.0.tar.xz
-
-          pushd git-2.15.0 >/dev/null
-            make prefix="${RUNNER_TEMP}/git-2.15.0" -j"$(nproc)" all
-            make prefix="${RUNNER_TEMP}/git-2.15.0" install
-          popd >/dev/null
-
-          echo "${RUNNER_TEMP}/git-2.15.0/bin" >> "$GITHUB_PATH"
-
-      - name: Verify Git version
-        shell: bash
-        run: |
-          set -euo pipefail
-          test "$(git --version | awk '{print $3}')" = "2.15.0"
-
-      - name: Prepare local fixture repository
-        shell: bash
-        run: |
-          set -euo pipefail
-
-          git init --bare remote.git
-          git init .
-          git config user.email "ci@example.com"
-          git config user.name "CI"
-          git checkout -b main
-
-          echo "fixture report" > report.html
-          git add report.html
-          git commit -m "init fixture"
-
-          git remote add origin "remote.git"
-          git push -u origin main
-
-      - name: Run action with explicit branch
-        uses: ./action-src
-        with:
-          coverage: "75%"
-          branch: main
-          report: report.html
-
-      - name: Verify Git 2.15.0 run
-        shell: bash
-        run: |
-          set -euo pipefail
-
-          files="$(git --git-dir=remote.git ls-tree --name-only -r coverage)"
-          echo "$files" | grep -Fx "main/badge.svg"
-          echo "$files" | grep -Fx "main/report.html"