Remove OstreeTlsCertInteraction bits from introspection

We filter out everything named `-private.h` from scanning,
which differs from the gtk-doc exclude.  Eventually this will
be solved when we switch to the new gir-based docs.

Came up in https://github.com/ostreedev/ostree-rs/pull/34#discussion_r723337772

src/libostree/ostree-fetcher-soup.c

@@ -35,7 +35,7 @@
 #include "ostree-fetcher.h"
 #include "ostree-fetcher-util.h"
 #ifdef HAVE_LIBSOUP_CLIENT_CERTS
-#include "ostree-tls-cert-interaction.h"
+#include "ostree-tls-cert-interaction-private.h"
 #endif
 #include "ostree-enumtypes.h"
 #include "ostree.h"

src/libostree/ostree-tls-cert-interaction.c

@@ -19,7 +19,7 @@
 
 #include "config.h"
 
-#include "ostree-tls-cert-interaction.h"
+#include "ostree-tls-cert-interaction-private.h"
 
 struct _OstreeTlsCertInteraction
 {