Remove unnecessary upstream file

Author: kzu

.github/workflows/dotnet-file-core.yml

@@ -136,6 +136,4 @@
 	weak
 [file ".github/workflows/dotnet-file-core.yml"]
 	url = https://github.com/devlooped/oss/blob/main/.github/workflows/dotnet-file-core.yml
-	sha = 875284ba5d565f529aba2f5d24ab8ed27c1d1c79
-	etag = 8de1d974bf73b1945b5c8be684c3a0b7364114a0d795c9d68837aed9b3aff331
-	weak
+	skip