Remove DSA key for Sparkle updates

Sparkle has deprecated signing updates with DSA for a long time. MacVim
has also added an EdDSA key for a while now. This means we can remove
the DSA key and still be pretty safe and certain that vast majority of
MacVim users can still update from old versions of MacVim to the new
one, using only the EdDSA key. This makes the update process easier and
we don't have to use legacy tools to sign each update with the
deprecated DSA key.

Author: ychin

src/MacVim/Info.plist

@@ -1309,8 +1309,6 @@
 	</array>
 	<key>SUFeedURL</key>
 	<string>https://raw.githubusercontent.com/macvim-dev/macvim/gh-pages/appcast/latest.xml</string>
-	<key>SUPublicDSAKeyFile</key>
-	<string>dsa_pub.pem</string>
 	<key>SUPublicEDKey</key>
 	<string>Pt4zsg/8S3/mxKW7Cmt0cZFw/+2LOuXOYS93evP+Mfc=</string>
 	<key>NSAppleEventsUsageDescription</key>

src/MacVim/MacVim.xcodeproj/project.pbxproj

@@ -66,7 +66,6 @@
 		528DA66A1426D4F9003380F1 /* macvim-askpass in Copy Scripts */ = {isa = PBXBuildFile; fileRef = 528DA6691426D4EB003380F1 /* macvim-askpass */; };
 		52A364731C4A5789005757EC /* Sparkle.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 52A364721C4A5789005757EC /* Sparkle.framework */; settings = {ATTRIBUTES = (Weak, ); }; };
 		52A364761C4A57C1005757EC /* Sparkle.framework in Copy Frameworks */ = {isa = PBXBuildFile; fileRef = 52A364721C4A5789005757EC /* Sparkle.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
-		52B7ED9B1C4A4D6900AFFF15 /* dsa_pub.pem in Resources */ = {isa = PBXBuildFile; fileRef = 52B7ED9A1C4A4D6900AFFF15 /* dsa_pub.pem */; };
 		8D11072B0486CEB800E47090 /* InfoPlist.strings in Resources */ = {isa = PBXBuildFile; fileRef = 089C165CFE840E0CC02AAC07 /* InfoPlist.strings */; };
 		8D11072D0486CEB800E47090 /* main.m in Sources */ = {isa = PBXBuildFile; fileRef = 29B97316FDCFA39411CA2CEA /* main.m */; settings = {ATTRIBUTES = (); }; };
 		8D11072F0486CEB800E47090 /* Cocoa.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 1058C7A1FEA54F0111CA2CBB /* Cocoa.framework */; };
@@ -959,7 +958,6 @@
 			isa = PBXResourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
-				52B7ED9B1C4A4D6900AFFF15 /* dsa_pub.pem in Resources */,
 				8D11072B0486CEB800E47090 /* InfoPlist.strings in Resources */,
 				1D0E051C0BA5F83800B6049E /* Colors.plist in Resources */,
 				1DD04DEC0C529C5E006CDC2B /* Credits.rtf in Resources */,