Fix breaking DiskStorage library tests (#2939)

Checking partition layouts uses a script with the `blkid` command. the output of which has recently changed to include a `DISKSEQ` field. Discard this before comparison.

Also includes commit which improves cache performance.

CI runner for Ubuntu 24 has dropped clang 15, so changed script to use the latest available (clang 18).

Author: mikee47

.github/workflows/ci.yml

@@ -45,7 +45,7 @@ jobs:
       SMING_HOME: ${{ github.workspace }}/Sming
       SMING_ARCH: ${{ matrix.arch }}
       SMING_SOC: ${{ matrix.variant }}
-      CLANG_BUILD: ${{ matrix.toolchain == 'clang' && '15' || '0' }}
+      CLANG_BUILD: ${{ matrix.toolchain == 'clang' && '18' || '0' }}
       BUILD64: ${{ matrix.toolchain == 'gcc64' && 1 || 0 }}
       ENABLE_CCACHE: 1
       CCACHE_DIR: ${{ github.workspace }}/.ccache