cabal install requires cpphs downgrade

Installing hothasktags under the latest haskell-platform requires a potentially destructive downgrade:
```
$ cabal install hothasktags
Resolving dependencies...
In order, the following would be installed:
cpphs-1.14 (new version)
haskell-src-exts-1.13.5 (reinstall) changes: cpphs-1.16 -> 1.14
hothasktags-0.3.0 (new package)
cabal: The following packages are likely to be broken by the reinstalls:
hoogle-4.2.15
hlint-1.8.43
HTF-0.10.0.7
Use --force-reinstalls if you want to install anyway.
```
I incremented hothasktag's upper bound on cpphs's version to avoid this.