os.json: Update kernel version automatically

export-noobs/00-release/00-run.sh

@@ -37,6 +37,7 @@ sed "${NOOBS_DIR}/os.json" -i -e "s|UNRELEASED|${IMG_DATE}|"
 sed "${NOOBS_DIR}/os.json" -i -e "s|NOOBS_NAME|${NOOBS_NAME}|"
 sed "${NOOBS_DIR}/os.json" -i -e "s|NOOBS_DESCRIPTION|${NOOBS_DESCRIPTION}|"
 sed "${NOOBS_DIR}/os.json" -i -e "s|RELEASE|${RELEASE}|"
+sed "${NOOBS_DIR}/os.json" -i -e "s|KERNEL|$(cat "${STAGE_WORK_DIR}/kernel_version")|"
 
 sed "${NOOBS_DIR}/release_notes.txt" -i -e "s|UNRELEASED|${IMG_DATE}|"
 

export-noobs/00-release/files/os.json

@@ -1,7 +1,7 @@
 {
     "description": "NOOBS_DESCRIPTION",
     "feature_level": 35120124,
-    "kernel": "4.19",
+    "kernel": "KERNEL",
     "name": "NOOBS_NAME",
     "password": "raspberry",
     "release_date": "UNRELEASED",