add support for mobi in makefile

Makefile

@@ -1,8 +1,8 @@
 SHELL := /bin/bash
 
-.SILENT: clean venv fetch merge epub words count
+.SILENT: dependencies clean venv fetch merge epub words count mobi
 
-all: 	clean venv fetch merge epub 
+all:  	clean venv fetch merge epub mobi
 
 clean: 
 		@echo "🗑 Cleaning up the room..."
@@ -18,14 +18,15 @@ count:
 venv:
 		@echo "🐍 Creating a safe place for a Python... "
 		mkdir essays
-		python3.8 -m venv .venv
+		python3.9 -m venv .venv
 		source ".venv/bin/activate"
 		pip install --upgrade pip
 		pip install -r requirements.txt
 
 dependencies: # for MacOS
-		brew install python3
+		brew install [email protected]
 		brew install --build-from-source pandoc
+		brew install --cask calibre
 
 fetch:	
 		@echo "🧠 Downloading Paul Graham mind... "
@@ -36,3 +37,9 @@ epub:
 		@echo "📒 Binding the EPUB... "
 		pandoc essays/*.md -o graham.epub -f markdown_strict --metadata-file=metadata.yaml --toc --toc-depth=1 --epub-cover-image=cover.png
 		@echo "🎉 EPUB file created."
+
+mobi:
+		${epub}
+		@echo "📒 Binding the MOBI... "
+		ebook-convert graham.epub graham.mobi
+		@echo "🎉 MOBI file created."