Use elpaca instead of straight

Some big changes related to that, and to use-package

lisp/themes/icejam-base16-harmonic-light.el

@@ -8,7 +8,6 @@
 ;;; Code:
 
 (declare-function base16-theme-define (theme-name colors))
-(use-package base16-theme :straight t :defer t)
 
 (defvar icejam-base16-harmonic-light-colors
   '(:base00 "#f7f9fb"
@@ -33,7 +32,9 @@
 (deftheme icejam-base16-harmonic-light)
 
 ;; Add all the faces to the theme
-(base16-theme-define 'icejam-base16-harmonic-light icejam-base16-harmonic-light-colors)
+(with-eval-after-load 'base16-theme
+  (base16-theme-define
+   'icejam-base16-harmonic-light icejam-base16-harmonic-light-colors))
 
 ;; Mark the theme as provided
 (provide-theme 'icejam-base16-harmonic-light)

lisp/themes/icejam-base16-not-harmonic.el

@@ -5,7 +5,7 @@
 ;; Based on harmonic-dark theme by Jannik Seibert (https://github.com/janniks)
 ;;; Code:
 
-(use-package base16-theme :straight t :defer t)
+(use-package base16-theme :ensure t :defer t)
 
 (defvar base16-not-harmonic-colors
   '(:base00 "#102941"

lisp/themes/icejam-base16-summerfruit-light.el

@@ -7,7 +7,7 @@
 
 ;;; Code:
 
-(use-package base16-theme :straight t :defer t)
+(use-package base16-theme :ensure t :defer t)
 
 (defvar base16-summerfruit-light-modified-colors
   '(:base00 "#fdfcfa"

lisp/themes/icejam-base16-zenburn.el

@@ -16,7 +16,6 @@
 ;; 04 made darker by 5%   #808080 => #7a7a7a
 ;; 0B made lighter by 10% #5f7f5f => #799979
 
-(use-package base16-theme :straight t)
 (declare-function base16-theme-define "base16-theme" (theme-name theme-colors))
 
 (defvar icejam-base16-zenburn-colors
@@ -42,7 +41,8 @@
 (deftheme icejam-base16-zenburn)
 
 ;; Add all the faces to the theme
-(base16-theme-define 'icejam-base16-zenburn icejam-base16-zenburn-colors)
+(with-eval-after-load 'base16-theme
+  (base16-theme-define 'icejam-base16-zenburn icejam-base16-zenburn-colors))
 
 ;; Mark the theme as provided
 (provide-theme 'icejam-base16-zenburn)