Bump xu-cheng/latex-action from 3 to 4

Bumps [xu-cheng/latex-action](https://github.com/xu-cheng/latex-action) from 3 to 4.
- [Release notes](https://github.com/xu-cheng/latex-action/releases)
- [Commits](xu-cheng/latex-action@v3...v4)

---
updated-dependencies:
- dependency-name: xu-cheng/latex-action
  dependency-version: '4'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/build-slides.yml

@@ -23,7 +23,7 @@ jobs:
       - name: Set up Git repository
         uses: actions/checkout@v6
       - name: Compile essentials
-        uses: xu-cheng/latex-action@v3
+        uses: xu-cheng/latex-action@v4
         if: matrix.version == 'essentials'
         with:
           root_file: C++Course.tex
@@ -33,7 +33,7 @@ jobs:
           working_directory: talk
           extra_system_packages: "py-pygments"
       - name: Compile full course
-        uses: xu-cheng/latex-action@v3
+        uses: xu-cheng/latex-action@v4
         if: matrix.version == 'full'
         with:
           root_file: C++Course.tex

.github/workflows/publish-slides.yml

@@ -16,7 +16,7 @@ jobs:
       - uses: actions/checkout@v6
       - name: Compile Essentials document
         if: matrix.version == 'essentials'
-        uses: xu-cheng/latex-action@v3
+        uses: xu-cheng/latex-action@v4
         with:
           root_file: C++Course.tex
           latexmk_use_xelatex: true
@@ -25,7 +25,7 @@ jobs:
           extra_system_packages: "py-pygments"
       - name: Compile Full document
         if: matrix.version == 'full'
-        uses: xu-cheng/latex-action@v3
+        uses: xu-cheng/latex-action@v4
         with:
           root_file: C++Course.tex
           latexmk_use_xelatex: true