Prepare for Release 1.2.8 (#6159)

Prepare for release 1.2.8 (with iot-identity-service 1.2.6)

## Azure IoT Edge PR checklist:

This checklist is used to make sure that common guidelines for a pull request are followed.

### General Guidelines and Best Practices
- [x] I have read the [contribution guidelines](https://github.com/azure/iotedge#contributing).
- [x] Title of the pull request is clear and informative.
- [x] Description of the pull request includes a concise summary of the enhancement or bug fix.

### Testing Guidelines
- [x] Pull request includes test coverage for the included changes.
- Description of the pull request includes 
	- [x] concise summary of tests added/modified
	- [x] local testing done.  

### Draft PRs
- Open the PR in `Draft` mode if it is:
	- Work in progress or not intended to be merged.
	- Encountering multiple pipeline failures and working on fixes.

_Note: We use the kodiakhq bot to merge PRs once the necessary checks and approvals are in place. When it merges a PR, kodiakhq converts the PR title to the commit title, PR description to the commit description, and squashes all the commits in the PR to a single commit. The net effect is that entire PR becomes a single commit. Please follow the best practices mentioned [here](https://chris.beams.io/posts/git-commit/#:~:text=The%20seven%20rules%20of%20a%20great%20Git%20commit,what%20and%20why%20vs.%20how%20For%20example%3A%20) for the PR title and description_

CHANGELOG.md

@@ -1,3 +1,26 @@
+# 1.2.8 (2021-02-24)
+## Edge Agent
+### Bug Fixes
+* Fix underflow possibility on ColumnFamilyDbStore  ( [bc78f1c](https://github.com/Azure/iotedge/commit/bc78f1c0b0ab0dfa305b817c030b82cea035f6e0) )
+* Remove BouncyCastle dependency ( [403ca87](https://github.com/Azure/iotedge/commit/403ca87bc228421c8913c1431687267dee9112a7), [7589457](https://github.com/Azure/iotedge/commit/7589457deec0f2735711cb8973cac0f0e17046c1) )
+* Update `Microsoft.Azure.Devices.Client` SDK ( [4b7570f](https://github.com/Azure/iotedge/commit/4b7570f12b2de0875e29b19964c935e693933e82) )
+
+
+## Edge Hub
+### Bug Fixes
+* Fix underflow possibility on ColumnFamilyDbStore  ( [bc78f1c](https://github.com/Azure/iotedge/commit/bc78f1c0b0ab0dfa305b817c030b82cea035f6e0) )
+* Remove BouncyCastle dependency ( [403ca87](https://github.com/Azure/iotedge/commit/403ca87bc228421c8913c1431687267dee9112a7), [7589457](https://github.com/Azure/iotedge/commit/7589457deec0f2735711cb8973cac0f0e17046c1) )
+* Restart EdgeHub upon certificate renewal ( [c5e90a7](https://github.com/Azure/iotedge/commit/c5e90a75e9a89ff612ad8c60241b0039464c298d) )
+* Update `Microsoft.Azure.Devices.Client` SDK ( [4b7570f](https://github.com/Azure/iotedge/commit/4b7570f12b2de0875e29b19964c935e693933e82) )
+* Workaround for windows-certificate import problem for EdgeHub in Visual Studio debug runs ( [0ed0c71](https://github.com/Azure/iotedge/commit/0ed0c710e2fc38c6feda7c39cb71b6625e20e87d) )
+
+
+## aziot-edge
+### Bug Fixes
+* Remove `sudo` from `iotedge check` for local proxy setting check ( [5976efb](https://github.com/Azure/iotedge/commit/5976efb411b3edfd860494e081ed835637c96529) )
+* Update vulnerable regex package ( [a34fd5b](https://github.com/Azure/iotedge/commit/a34fd5bca7e58c01819da56dd73df817fbefeb7e), [fe7de0b](https://github.com/Azure/iotedge/commit/fe7de0b45363594d1f23b575eddb2947d38ace6a) )
+
+
 # 1.2.7 (2021-01-19)
 ## Edge Agent
 ### Bug Fixes

edgelet/contrib/centos/aziot-edge.spec

@@ -17,7 +17,7 @@ URL:            https://github.com/azure/iotedge
 %{?systemd_requires}
 BuildRequires:  systemd
 Requires(pre):  shadow-utils
-Requires:       aziot-identity-service = 1.2.5-1
+Requires:       aziot-identity-service = 1.2.6-1
 Source0:        aziot-edge-%{version}.tar.gz
 
 %description

edgelet/contrib/debian/control

@@ -8,7 +8,7 @@ Homepage: https://github.com/azure/iotedge
 
 Package: aziot-edge
 Architecture: any
-Depends: ${misc:Depends}, ${shlibs:Depends}, adduser, ca-certificates, hostname, aziot-identity-service (= 1.2.5-1), sed
+Depends: ${misc:Depends}, ${shlibs:Depends}, adduser, ca-certificates, hostname, aziot-identity-service (= 1.2.6-1), sed
 Description: Azure IoT Edge Module Runtime
  Azure IoT Edge is a fully managed service that delivers cloud intelligence
  locally by deploying and running artificial intelligence (AI), Azure services,

edgelet/version.txt

@@ -1 +1 @@
-1.2.7
+1.2.8

versionInfo.json

@@ -1,5 +1,5 @@
 {
-  "version": "1.2.7",
+  "version": "1.2.8",
   "build": "BUILDNUMBER",
   "commit": "COMMITID"
 }