Automatically update Version in R package

Question

I'd like to automatically update Version in R package DESCRIPTION file on every merge after pull request. Are there any tools, hooks, etc. created to do this job? Or maybe it is not good approach to the matter?

Here is example DESCRIPTION file:

Package: app
Title: Test version of app
Version: 0.9.4
Date: 2017-09-01
Description: example app
License: 
Encoding: UTF-8
LazyData: true
RoxygenNote: 6.0.1
Depends:
    R (>= 3.3.1),
    Biobase,
    shiny,
    R6,
    shinyjs,
    grid,
    RColorBrewer
Suggests:
    testthat,
    lintr,
    png,
    knitr
Imports:
    magrittr,
    binom,
    ggplot2,
    gplots,
    Hmisc,
    MASS,
    nlme