fix(git): support numeric branch names

gitGraph does not support branch names that start with a number,
because the gitGraph.jison file parses these as NUM (number) instead.

To fix this, I've changed the NUM parser to only accept strings that
end with whitespace (e.g 1234 is a NUM, but 1234abc is not a NUM).
To do this, I had to move the "skip all whitespace" step to the
end of the parser, but this doesn't seem to have caused any issues,
so it's probably fine.

src/diagrams/git/gitGraphParserV2.spec.js

@@ -348,6 +348,21 @@ describe('when parsing a gitGraph', function () {
     expect(Object.keys(parser.yy.getBranches()).length).toBe(2);
   });
 
+  it('should allow branch names starting with numbers', function () {
+    const str = `gitGraph:
+    commit
+    %% branch names starting with numbers are not recommended, but are supported by git
+    branch 1.0.1
+    `;
+
+    parser.parse(str);
+    const commits = parser.yy.getCommits();
+    expect(Object.keys(commits).length).toBe(1);
+    expect(parser.yy.getCurrentBranch()).toBe('1.0.1');
+    expect(parser.yy.getDirection()).toBe('LR');
+    expect(Object.keys(parser.yy.getBranches()).length).toBe(2);
+  });
+
   it('should handle new branch checkout', function () {
     const str = `gitGraph:
     commit