build: update gh actions

Author: kyeh-amp

.github/workflows/docs.yml

@@ -10,7 +10,7 @@ jobs:
         uses: actions/checkout@v2
 
       - name: Set up Python
-        uses: actions/setup-python@v3
+        uses: actions/setup-python@v6
 
       - name: Set up pdoc
         run:  pip install pdoc3

.github/workflows/publish-to-pypi.yml

@@ -32,7 +32,7 @@ jobs:
           fetch-depth: 0
 
       - name: Set up Python 3.8
-        uses: actions/setup-python@v3
+        uses: actions/setup-python@v6
         with:
           python-version: 3.8
 

.github/workflows/publish-to-test-pypi.yml

@@ -22,7 +22,7 @@ jobs:
       - uses: actions/checkout@v3
 
       - name: Set up Python 3.8
-        uses: actions/setup-python@v3
+        uses: actions/setup-python@v6
         with:
           python-version: 3.8