gitignore: ignore binaries only in top level

This rules was ignoring also src/* directories.
7 jobs for fix-invalid-hash in 5 minutes and 16 seconds (queued for 7 seconds)
Status Job ID Name Coverage
  Build
passed #378613
build-alpine

00:01:19

passed #378611
build-debian-stable

00:01:14

passed #378612
build-debian-unstable

00:01:14

 
  Test
passed #378614
check

00:01:54

passed #378616
lint-c

00:00:48

passed #378617
lint-lua

00:00:49

passed #378615
valgrind-memcheck

00:03:57