[ci] Fix check-symbols failing on ubuntu-latest (#9)

Author: swift-kim

.github/workflows/build.yml

@@ -4,7 +4,7 @@ on: [push, pull_request]
 
 jobs:
   build:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-latest
 
     strategy:
       matrix:

tools/check_symbols.py

@@ -21,7 +21,8 @@ def __str__(self):
 
   @staticmethod
   def parse(line):
-    return Symbol(line[:8].strip(), line[9], line[11:].strip())
+    # Format: "         U abort@GLIBC_2.4" (addr can be empty)
+    return Symbol(line[:8].strip(), line[9], line[11:].strip().split('@')[0])
 
 
 def check_symbol(sofile, allowlist):