Attempt match on empty string

As the new test illustrates, a Kleene star pattern followed by `$` does,
in fact, match, but only on the empty string.  With this patch mvzr will
try a final pattern match on the empty string before giving up.

build.zig.zon

@@ -7,7 +7,7 @@
 
     // This is a [Semantic Version](https://semver.org/).
     // In a future version of Zig it will be used for package deduplication.
-    .version = "0.2.3",
+    .version = "0.2.4",
 
     // This field is optional.
     // This is currently advisory only; Zig does not yet do anything

src/mvzr.zig

@@ -204,7 +204,7 @@ pub fn SizedRegex(ops: comptime_int, char_sets: comptime_int) type {
                 },
                 else => {
                     var matchlen: usize = 0;
-                    while (matchlen < haystack.len) : (matchlen += 1) {
+                    while (matchlen <= haystack.len) : (matchlen += 1) {
                         const matched = matchOuterPattern(patt, &regex.sets, haystack, matchlen);
                         if (matched) |m| {
                             return .{ matchlen, m.i };
@@ -2224,3 +2224,8 @@ test "repetition and word break" {
     const regex = Regex.compile("[de]{2,}\\b").?;
     try expect(!regex.isMatch("defense"));
 }
+
+test "match end" {
+    const regex = Regex.compile("a*$").?;
+    try std.testing.expect(regex.isMatch("bb"));
+}