lgtm: fix for tss version

TSS now uses the git-describe for version so the master zip archive
provided by GitHub no longer works.

Signed-off-by: William Roberts <william.c.roberts@intel.com>

.lgtm.yml

@@ -4,12 +4,12 @@ extraction:
       packages:
       - autoconf-archive
       - acl
+      - git
     after_prepare:
     - cd "$LGTM_WORKSPACE"
     - mkdir installdir
-    - wget https://github.com/tpm2-software/tpm2-tss/archive/master.tar.gz
-    - tar xf master.tar.gz
-    - cd tpm2-tss-master
+    - git clone https://github.com/tpm2-software/tpm2-tss.git
+    - cd tpm2-tss
     - ./bootstrap
     - ./configure --prefix="$LGTM_WORKSPACE/installdir/usr" --disable-doxygen-doc --disable-esys --disable-fapi
     - make install