proto: Change the default checksum from md5 to sha256

MD5 isn't a very good checksum, and the PKGBUILD page on the Arch Wiki
states that it should not be used, instead recommending sha256 or b2.
This patch changes the default from md5 to sha256 because that seems to
be the most commonly used checksum today.

Signed-off-by: Ben Westover <kwestover.kw@gmail.com>

proto/PKGBUILD-split.proto

@@ -28,7 +28,7 @@ changelog=
 source=("$pkgbase-$pkgver.tar.gz"
         "$pkgname-$pkgver.patch")
 noextract=()
-md5sums=()
+sha256sums=()
 validpgpkeys=()
 
 prepare() {

proto/PKGBUILD-vcs.proto

@@ -25,7 +25,7 @@ options=()
 install=
 source=('FOLDER::VCS+URL#FRAGMENT')
 noextract=()
-md5sums=('SKIP')
+sha256sums=('SKIP')
 
 # Please refer to the 'USING VCS SOURCES' section of the PKGBUILD man page for
 # a description of each element in the source array.

proto/PKGBUILD.proto

@@ -27,7 +27,7 @@ changelog=
 source=("$pkgname-$pkgver.tar.gz"
         "$pkgname-$pkgver.patch")
 noextract=()
-md5sums=()
+sha256sums=()
 validpgpkeys=()
 
 prepare() {