build: add *~ to .gitignore

Homebrew autoconf version 2.7.1 introduces configure~ as a build artifact.

Co-authored-by: Hennadii Stepanov <32963518+hebasto@users.noreply.github.com>

.gitignore

@@ -61,7 +61,7 @@ src/qt/bitcoin-qt.includes
 .dirstamp
 .libs
 .*.swp
-*.*~*
+*~
 *.bak
 *.rej
 *.orig