alpine: use /bin/sh as a default interpreter
diff --git a/alpine/Makefile b/alpine/Makefile
index 0b39bba..17ea87f 100644
--- a/alpine/Makefile
+++ b/alpine/Makefile
@@ -1,4 +1,4 @@
-SHELL=		/bin/bash
+SHELL=		/bin/sh
 
 BASE_VERSION=	1.19.4
 BASE_RELEASE=	1