build(deps): bump actions/checkout from 3 to 4

Bumps [actions/checkout](https://github.com/actions/checkout) from 3 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...v4)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

.github/workflows/main.yml

@@ -24,7 +24,7 @@ jobs:
 
     steps:
       - name: Checkout repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup Intel Fortran Classic
         uses: awvwgk/setup-fortran@main

.github/workflows/pymake-gcc.yml

@@ -24,7 +24,7 @@ jobs:
 
     steps:
       - name: Checkout repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup Graphviz on Linux
         if: runner.os == 'Linux'
@@ -83,7 +83,7 @@ jobs:
 
     steps:
       - name: Checkout repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup Graphviz
         uses: ts-graphviz/setup-graphviz@v1
@@ -142,7 +142,7 @@ jobs:
 
     steps:
       - name: Checkout repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v4.3.0

.github/workflows/pymake-linting-install.yml

@@ -19,7 +19,7 @@ jobs:
     if: github.repository_owner == 'modflowpy'
     steps:
       - name: Checkout repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Set up Python
         uses: actions/setup-python@v4.3.0
@@ -72,7 +72,7 @@ jobs:
 
       # check out repo
       - name: Checkout pymake repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup Python
         uses: actions/setup-python@v4.3.0

.github/workflows/pymake-requests.yml

@@ -20,7 +20,7 @@ jobs:
 
     steps:
       - name: Checkout repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Set up Python
         uses: actions/setup-python@v4.3.0

.github/workflows/pymake-rtd.yml

@@ -18,7 +18,7 @@ jobs:
       github.event_name == 'push'
     steps:
       - name: Checkout repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Trigger RTDs build
         if: github.ref == 'refs/heads/master'