[libpeas] Fix typo introduced in #20

[Rico Tzschichholz <ricotz src gnome org>]

commit 744a06559b57236764cf4cac04104447ea86b9ab
Author: Christopher Arndt <chris chrisarndt de>
Date:   Wed Oct 30 16:51:36 2019 +0100

    Fix typo introduced in #20
    
    Signed-off-by: Christopher Arndt <chris chrisarndt de>

 meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index 05439d5..5abb4bb 100644
--- a/meson.build
+++ b/meson.build
@@ -129,7 +129,7 @@ if (luajit_dep.found() and luajit_prg.found()) or (lua51_dep.found() and lua51_p
     if luajit_prg.found()
         lua_prg = luajit_prg
     else
-        lua_prf = lua51_prg
+        lua_prg = lua51_prg
     endif
     lua_lgi_check = run_command(lua_prg, ['-e', 'print(require("lgi")._VERSION)'])
     if lua_lgi_check.returncode() == 0