twister: add 12 hexadecimal digits to version

With the earlier version of Git, git describe command will
use the default 7 hexadecimal digits as the abbreviated
object name. But currently the Linux kernel project needs
11 to 12 hexdigits to stay unique.So it's necessary to add
--abbrev=12 to ensure twister always generate the same tags.

In https://testing.zephyrproject.org/daily_tests/versions.json,
all tags have 10 hexadecimal digits.

Signed-off-by: Jingru Wang <[email protected]>

Author: wangnuannuan

scripts/pylib/twister/twisterlib.py

@@ -2580,7 +2580,7 @@ def __init__(self, board_root_list=[], testcase_roots=[], outdir=None):
 
     def check_zephyr_version(self):
         try:
-            subproc = subprocess.run(["git", "describe"],
+            subproc = subprocess.run(["git", "describe", "--abbrev=12"],
                                      stdout=subprocess.PIPE,
                                      universal_newlines=True,
                                      cwd=ZEPHYR_BASE)