manifest.scm: Move guix package deps from .envrc to a manifest file

.envrc

@@ -9,7 +9,7 @@ use_guix-shell() {
   fi
 }
 
-use guix-shell gcc-cross-avr-toolchain avrdude dfu-util dfu-programmer make python-wrapper qmk git coreutils sed grep bash gawk diffutils
+use guix-shell -m manifest.scm
 
 # TODO: currently the following needs to be set to allow the linker to find avr-libc
 # See: https://issues.guix.gnu.org/69394

manifest.scm

@@ -0,0 +1,15 @@
+(specifications->manifest
+ '("avrdude"
+   "bash"
+   "coreutils"
+   "dfu-programmer"
+   "dfu-util"
+   "diffutils"
+   "gawk"
+   "gcc-cross-avr-toolchain"
+   "git"
+   "grep"
+   "make"
+   "python-wrapper"
+   "qmk"
+   "sed"))