v0.21.0

• b225462 Support custom queries in builder (#403) by @Serdnad
• af36d1e Add a to_json method for Granite::Error (#401) by @3n-k1
• 1daaa35 Fix read_attribute, see #396 (#397) by @msa7
• 536a9b4 Fix #394 by stripping the module name from the table name (#395) by @3n-k1
• 3d849eb Fix: Ensure Granite::Error#to_s returns string (#386) by @akadusei
• 2dee196 Add empty "else" statement for compatibility with Crystal 0.34.0 (#399) by @MrSorcus
• fde10ca Replace deprecated Logger via Log. (#398) @MrSorcus