DB Browser for SQLite 3.12.0

Update version number for 3.12.0

Updating version number for 3.12.0-rc1

We're using 3.11.300 for the 3.12.0-rc1, in order to keep
numerically lower than 3.12.0, which will be used for the
actual release.

Only include the build date for nightly builds.

Our alpha and beta releases use patch numbers greater than 99, so
were being caught by the version string check.

Update version number to 3.11.2

The rebuilt macOS installer (v2) was generated from this tag.

Update version number to 3.11.1

We're using Qt 5.11.3 for the Win64 builds

The DB4S 3.11.0-beta3 Win32/64 & macOS binaries were created from

this commit.

The DB4S 3.11.0-beta2 Win32/64 & macOS binaries were created from thi…

…s commit.