Update CHANGELOG.md (dart-lang/pub_semver#81)

diff --git a/pkgs/pub_semver/CHANGELOG.md b/pkgs/pub_semver/CHANGELOG.md
index 8c394e3..057895a 100644
--- a/pkgs/pub_semver/CHANGELOG.md
+++ b/pkgs/pub_semver/CHANGELOG.md
@@ -1,31 +1,34 @@
-# 2.1.3
+## 2.1.4-dev
+
+## 2.1.3
 
 - Add type parameters to the signatures of the `Version.preRelease` and
   `Version.build` fields (`List` ==> `List<Object>`).
   [#74](https://github.com/dart-lang/pub_semver/pull/74).
 - Require Dart 2.17.
 
-# 2.1.2
+## 2.1.2
 
 - Add markdown badges to the readme.
 
-# 2.1.1
+## 2.1.1
 
 - Fixed the version parsing pattern to only accept dots between version
   components.
 
-# 2.1.0
+## 2.1.0
+
 - Added `Version.canonicalizedVersion` to help scrub leading zeros and highlight
   that `Version.toString()` preserves leading zeros.
 - Annotated `Version` with `@sealed` to discourage users from implementing the
   interface.
 
-# 2.0.0
+## 2.0.0
 
 - Stable null safety release.
 - `Version.primary` now throws `StateError` if the `versions` argument is empty.
 
-# 1.4.4
+## 1.4.4
 
 - Fix a bug of `VersionRange.union` where ranges bounded at infinity would get
   combined wrongly.
@@ -35,16 +38,16 @@
 - Update Dart SDK constraint to `>=2.0.0 <3.0.0`.
 - Update `package:collection` constraint to `^1.0.0`.
 
-# 1.4.2
+## 1.4.2
 
 * Set max SDK version to `<3.0.0`.
 
-# 1.4.1
+## 1.4.1
 
 * Fix a bug where there upper bound of a version range with a build identifier
   could accidentally be rewritten.
 
-# 1.4.0
+## 1.4.0
 
 * Add a `Version.firstPreRelease` getter that returns the first possible
   pre-release of a version.
@@ -66,41 +69,41 @@
   disables the replacement described above and allows users to create ranges
   that do include the pre-release versions of an exclusive max version.
 
-# 1.3.7
+## 1.3.7
 
 * Fix more bugs with `VersionRange.intersect()`, `VersionRange.difference()`,
   and `VersionRange.union()` involving version ranges with pre-release maximums.
 
-# 1.3.6
+## 1.3.6
 
 * Fix a bug where constraints that only allowed pre-release versions would be
   parsed as empty constraints.
 
-# 1.3.5
+## 1.3.5
 
 * Fix a bug where `VersionRange.intersect()` would return incorrect results for
   pre-release versions with the same base version number as release versions.
 
-# 1.3.4
+## 1.3.4
 
 * Fix a bug where `VersionRange.allowsAll()`, `VersionRange.allowsAny()`, and
   `VersionRange.difference()` would return incorrect results for pre-release
   versions with the same base version number as release versions.
 
-# 1.3.3
+## 1.3.3
 
 * Fix a bug where `VersionRange.difference()` with a union constraint that
   covered the entire range would crash.
 
-# 1.3.2
+## 1.3.2
 
 * Fix a checked-mode error in `VersionRange.difference()`.
 
-# 1.3.1
+## 1.3.1
 
 * Fix a new strong mode error.
 
-# 1.3.0
+## 1.3.0
 
 * Make the `VersionUnion` class public. This was previously used internally to
   implement `new VersionConstraint.unionOf()` and `VersionConstraint.union()`.
@@ -112,21 +115,21 @@
 * Make `VersionRange` implement `Comparable<VersionRange>`. Ranges are ordered
   first by lower bound, then by upper bound.
 
-# 1.2.4
+## 1.2.4
 
 * Fix all remaining strong mode warnings.
 
-# 1.2.3
+## 1.2.3
 
 * Addressed three strong mode warnings.
 
-# 1.2.2
+## 1.2.2
 
 * Make the package analyze under strong mode and compile with the DDC (Dart Dev
   Compiler). Fix two issues with a private subclass of `VersionConstraint`
   having different types for overridden methods.
 
-# 1.2.1
+## 1.2.1
 
 * Allow version ranges like `>=1.2.3-dev.1 <1.2.3` to match pre-release versions
   of `1.2.3`. Previously, these didn't match, since the pre-release versions had
@@ -134,7 +137,7 @@
   added if they also have the same major, minor, and patch numbers as the min
   *and* the min is also a pre-release version.
 
-# 1.2.0
+## 1.2.0
 
 * Add a `VersionConstraint.union()` method and a `new
   VersionConstraint.unionOf()` constructor. These each return a constraint that
@@ -148,7 +151,7 @@
 
 * `Version` now implements `VersionRange`.
 
-# 1.1.0
+## 1.1.0
 
 * Add support for the `^` operator for compatible versions according to pub's
   notion of compatibility. `^1.2.3` is equivalent to `>=1.2.3 <2.0.0`; `^0.1.2`
@@ -162,6 +165,6 @@
 
 * Add a custom `VersionRange.hashCode` to make it properly hashable.
 
-# 1.0.0
+## 1.0.0
 
 * Initial release.