Update actions/upload-artifact action to v6

Author: renovate[bot]

.github/workflows/build_bootstrap_images_aarch64.yaml

@@ -156,7 +156,7 @@ jobs:
       #Artifacts
       - name: Upload (Build) Artifacts
         if: env.HAS_IMAGE == 'TRUE'
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
             name: "ARTIFACTS-${{ matrix.image }}_${{ matrix.arch }}"
             path: |

.github/workflows/build_bootstrap_images_x86_64.yaml

@@ -155,7 +155,7 @@ jobs:
       #Artifacts
       - name: Upload (Build) Artifacts
         if: env.HAS_IMAGE == 'TRUE'
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
             name: "ARTIFACTS-${{ matrix.image }}_${{ matrix.arch }}"
             path: |

.github/workflows/fetch_runner_images.yaml

@@ -209,7 +209,7 @@ jobs:
 
       #Artifacts
       - name: Upload (Build) Artifacts
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
             name: "gh-${{ matrix.image }}"
             path: |