chore: add invidious.o file to .gitignore

.gitignore

@@ -10,3 +10,8 @@
 
 # direnv directory used for the Nix Flake.
 .direnv
+
+# Invidious object file that gets generated when compiling
+# Invidiois with `--cross-compile` argument
+# Example: `crystal build src/invidious.cr --cross-compile`
+/invidious.o