[skip ci] updated version in version.py as 2.0.7

## 2.0.7

[skip ci] added ## next to RELEASE.md

[skip ci] updated version in version.py as 2.0.6

## 2.0.6

[skip ci] added ## next to RELEASE.md

[skip ci] updated version in version.py as 2.0.5

## 2.0.5

[skip ci] added ## next to RELEASE.md

[skip ci] updated version in version.py as 2.0.4

## 2.0.4

Merge branch 'develop' of github.com:openergy/opyplus into develop

## 2.0.4

[skip ci] added ## next to RELEASE.md

[skip ci] updated version in version.py as 2.0.3