E3-822: Register dependencies for expanded db files

This follows the same pattern as the .d files generated during compilation; the .d files are generated as a side effect of generating the output file, and we then include them all at build-time to register the correct dependencies. See line 634 of driver.makefile.

CHANGELOG.md

@@ -13,6 +13,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   * It is no longer necessary to specify `REQUIRED += ...` nor `x_VERSION = $(X_DEP_VERSION)` within the module makefile
 
 ### Bugfixes
+* Fixed issue where updated dependencies of substitution files did not retrigger a .db expansion.
 
 ### Other changes