chore: pin actions in workflows to commit hashes

**Description**:

Pin all actions used in `.github/workflows` to specific commit hashes.

**Related Issue(s)**:

Implements #321

Signed-off-by: Andrew Brandt <brandt.andrew89@gmail.com>

.github/workflows/ci.yml

@@ -1,5 +1,5 @@
 name: CI
-'on':
+on:
   push:
     branches: [master]
   pull_request:
@@ -7,12 +7,12 @@ name: CI
 jobs:
   build:
     runs-on: ubuntu-latest
-
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
           submodules: recursive
-      - uses: actions/setup-python@v6
+
+      - uses: actions/setup-python@83679a892e2d95755f2dac6acb0bfd1e9ac5d548 # v6.1.0
         with:
           python-version: '3.14'
 

.github/workflows/release.yml

@@ -9,16 +9,16 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
           submodules: recursive
-      - uses: actions/cache@v5
+      - uses: actions/cache@9255dc7a253b0ccc959486e2bca901246202afeb # v5.0.1
         with:
           path: |
             ~/.cache/pip
             ~/.platformio/.cache
           key: ${{ runner.os }}-pio
-      - uses: actions/setup-python@v6
+      - uses: actions/setup-python@83679a892e2d95755f2dac6acb0bfd1e9ac5d548 # v6.1.0
         with:
           python-version: '3.14'
 
@@ -29,7 +29,7 @@ jobs:
         run: pio run -e gh_release
 
       - name: Upload Artifacts
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
           name: CrossPoint-${{ github.ref_name }}
           path: |