tests,misc: Update DRAMSys test clone command

This clone is updated to reflect the new advice given in
ext/dramasys/README that was introduced in PR
https://github.com/gem5/gem5/pull/525 to upgrade DRAMSysm to v5.0.

Change-Id: I868619ecc1a44298dd3885e5719979bdaa24e9c2

.github/workflows/weekly-tests.yaml

@@ -89,11 +89,7 @@ jobs:
 
             - name: Checkout DRAMSys
               working-directory: ${{ github.workspace }}/ext/dramsys
-              run: |
-                  git clone https://github.com/tukl-msd/DRAMSys DRAMSys
-                  cd DRAMSys
-                  git checkout -b gem5 09f6dcbb91351e6ee7cadfc7bc8b29d97625db8f
-                  git submodule update --init --recursive
+              run: git clone https://github.com/tukl-msd/DRAMSys --branch v5.0 --depth 1 DRAMSys
 
       # gem5 is built separately because it depends on the DRAMSys library
             - name: Build gem5