Use dashes instead of underscores for METADATA.toml field names (#15614)

stubs/gdb/METADATA.toml

@@ -1,8 +1,8 @@
 version = "16.3.*"
 # This is the official web portal for the GDB Git repo,
 # see https://sourceware.org/gdb/current/ for other ways of obtaining the source code.
-upstream_repository = "https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=tree"
-extra_description = """\
+upstream-repository = "https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=tree"
+extra-description = """\
   Type hints for GDB's \
   [Python API](https://sourceware.org/gdb/onlinedocs/gdb/Python-API.html). \
   Note that this API is available only when running Python scripts under GDB: \
@@ -12,5 +12,5 @@ extra_description = """\
 
 [tool.stubtest]
 skip = true                # https://github.com/python/typeshed/issues/15236
-ci_platforms = ["linux"]
-apt_dependencies = ["gdb"]
+ci-platforms = ["linux"]
+apt-dependencies = ["gdb"]